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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.35, #1)

An ion-responsive motif in the second transmembrane segment of rhodopsin-like receptors by M. S. Parker; Y. Y. Wong; S. L. Parker (pp. 1-15).

A L(M)xxxD(N, E) motif (x=a non-ionic amino acid residue, most frequently A, S, L or F; small capitals indicating a minor representation) is found in the second transmembrane (tm2) segment of most G-protein coupling metazoan receptors of the rhodopsin family (Rh-GPCRs). Changes in signal transduction, agonist binding and receptor cycling are known for numerous receptors bearing evolved or experimentally introduced mutations in this tm2 motif, especially of its aspartate residue. The [Na⁺] sensitivity of the receptor-agonist interaction relates to this aspartate in a number of Rh-GPCRs. Native non-conservative mutations in the tm2 motif only rarely coincide with significant changes in two other ubiquitous features of the rhodopsin family, the seventh transmembrane N(D)PxxY(F) motif and the D(E)RY(W,F) or analogous sequence at the border of the third transmembrane helix and the second intracellular loop. Native tm2 mutations with Rh-GPCRs frequently result in constitutive signaling, and with visual opsins also in shifts to short-wavelength sensitivity. Substitution of a strongly basic residue for the tm2 aspartate in Taste-2 receptors could be connected to a lack of sodium sensing by these receptors. These properties could be consistent with ionic interactions, and even of ion transfer, that involve the tm2 motif. A decrease in cation sensing by this motif is usually connected to an enhanced constitutive interaction of the mutated receptors with cognate G- proteins, and also relates to both the constitutive and the overall activity of the short-wavelength opsins.

Keywords: Keywords: Ion switch – Signal transduction – Constitutive transduction – G-protein coupling – Ion transfer – Visual signaling

Role of neuronal nitric oxide synthase in the regulation of the neuroendocrine stress response in rodents: insights from mutant mice by G. F. Orlando; G. Wolf; M. Engelmann (pp. 17-27).

Nitric oxide (NO) is a free radical gas synthesised from arginine and oxygen by enzymes of the family of the nitric oxide synthase. In particular, the neuronal nitric oxide synthase (nNOS) is highly expressed by cells of the hypothalamic paraventricular nucleus, where the sympatho-adrenal system, the hypothalamic-pituitary-adrenal axis and the hypothalamic-neurohypophyseal system originate. These structures are deputed to regulate the neuroendocrine stress response. In the past years, evidence has been accumulated to suggest that NO of nNOS origin plays a significant role in modulating the activity of the above mentioned systems under acute stressor exposure. The availability of nNOS knock-out mice allowed to investigate not only the physiological consequences of a constitutive lack of NO of nNOS origin at the hormonal and molecular level, but also to examine possible behavioural alterations. In this review, we shall discuss and confront the current trends of research in this area, especially focusing on the latest findings gained from genetically modified mice.

Keywords: Keywords: Neuronal nitric oxide synthase – Hypothalamus – Neuroendocrine stress response – Knock-out mice – Catecholamine – Glucocorticoids

Advanced glycation end-products (AGEs): involvement in aging and in neurodegenerative diseases by M. A. Grillo; S. Colombatto (pp. 29-36).

Advanced glycation end-products (AGEs) are formed from the so-called Amadori products by rearrangement followed by other reactions giving rise to compounds bound irreversibly. The structure of some of them is shown and the mechanism of formation is described. Several AGE binding molecules (Receptors for AGE, RAGE) are known and it is thought that many of the effects caused by AGEs are mediated by RAGE. Some of these were shown to be toxic, and called TAGE. The mechanism of detoxification of glyoxal and methylglyoxal by the glyoxalase system is described and also the possibility to eliminate glycated proteins by deglycation enzymes. Compounds able to inhibit AGEs formation are also taken into consideration.

Keywords: Keywords: RAGE – TAGE – Detoxification – Amadorines

Synthesis of a bicyclic δ-amino acid as a constrained Gly-Asn dipeptide isostere by A. Trabocchi; G. Menchi; E. Danieli; A. Guarna (pp. 37-44).

δ-Amino acids are very attractive in drug discovery, especially in the peptidomimetic area, because of their capability to act as dipeptide isosteres and reverse turn mimetics. Herein we report the synthesis of a rigid δ-amino acid constrained by a 3-aza-6,8-dioxabicyclo[3.2.1]octane-based scaffold, which can be considered as a Gly-Asn dipeptide mimetic. Key steps are the condensation of glycidol and tartaric acid derivatives, and the intramolecular trans-acetalization of the oxidized adduct to give the bicyclic δ-amino acid. Starting from L-tartaric acid derivative, it was achieved the corresponding Gly-D-Asn isostere, whereas from the enantiomeric D-tartaric acid derivative the corresponding Gly-L-Asn isostere could be obtained, thus giving access to both enantiomeric dipeptide sequences.

Keywords: Keywords: Amino acids – Peptides – Peptidomimetics – Bicyclic compounds – Chiral pool

Effect of histamine on the signal transduction of the AtoS–AtoC two component system and involvement in poly-(R)-3-hydroxybutyrate biosynthesis in Escherichia coli by D. A. Kyriakidis; M. C. Theodorou; P. S. Filippou; K. D. Kyriakidis; E. Tiligada (pp. 45-52).

AtoS–AtoC two-component system acts directly on the atoDAEB operon transcription to regulate the biosynthesis of short-chain poly-(R)-3-hydroxybutyrate. This study sought to investigate the effect of histamine and compound 48/80 on the regulation of AtoS–AtoC two-component system in Escherichia coli K-12 MA255 (speC ⁻, speB ⁻) and the isogenic E. coli strains BW25113 (atoSC ⁺) and BW28878 (ΔatoSC) transformed with plasmids carrying related genes. Histamine or compound 48/80 induced or tended to reduce atoC transcription, respectively, while neither compound showed any effect on atoDAEB operon transcription. Moreover, histamine down-regulated poly-(R)-3-hydroxybutyrate biosynthesis, whereas compound 48/80 up-regulated its biosynthesis, maximal induction being obtained in the presence of multiple copies of AtoS–AtoC. Interestingly, co-administration of histamine counteracted this inductive effect of compound 48/80. The reported data provide the first evidence for a differential modulator role of histamine and compound 48/80 on the AtoS–AtoC two-component system signaling in potentially pathogenic bacteria, leading to a new perspective on their symbiotic behavior.

Keywords: Keywords: AtoS–AtoC – Compound 48/80 – Escherichia coli – Histamine – Poly-(R)-3-hydroxybutyrate – Two-component system

Production of hypotaurine from l-cysteinesulfinate by rat liver mitochondria by T. Ubuka; A. Okada; H. Nakamura (pp. 53-58).

Hypotaurine is the precursor of taurine production from l-cysteinesulfinate. It is recognized that hypotaurine production in the liver occurs in cytosol. In the present study, hypotaurine production from l-cysteinesulfinate in rat liver mitochondria was investigated. The mitochondrial preparation prepared according to the method of Hogeboom and washed repeatedly with 0.25 M sucrose solution was incubated with l-cysteinesulfinate. Products were derivatized with dabsyl chloride and dabsylated amino acids were analyzed by RP-HPLC. Presence of a peak corresponding to dabsyl-hypotaurine was confirmed. The peak of dabsyl-hypotaurine was converted quantitatively to dabsyl-taurine by the treatment with H₂O₂. Optimum pH of the reaction was shown to be broad between 6.0 and 7.8 and Km for l-cysteinesulfinate was 0.11 mM. Results indicate the presence of l-cysteinesulfinate decarboxylase activity in liver mitochondria. Mitochondrial cysteine metabolism was summarized and possible antioxidant roles of cysteine metabolites including hypotaurine in mitochondria are discussed.

Keywords: Keywords: Amino acids – Hypotaurine – l-Cysteinesulfinate decarboxylase – Liver mitochondria – Cysteine metabolism – Antioxidant

Metabolism of tryptophan, methionine and arginine in Diplodus sargus larvae fed rotifers: effect of amino acid supplementation by M. Saavedra; L. E. C. Conceição; P. Pousão-Ferreira; M. T. Dinis (pp. 59-64).

Dietary amino acids imbalances have been described when fish larvae are fed rotifers, what may lead to a reduction in growth rate. The tube-feeding technique can be used to assess the effect of free amino acid short term supplementation. In this study supplementation of tryptophan, methionine and arginine were tested in Diplodus sargus. Single crystalline ¹⁴C amino acids as well as a mix of ¹⁴C amino acids were used as tracers to compare results of individual amino acids metabolism with the average of all amino acids. The results show low absorption efficiencies for tryptophan (70%) and arginine (80%) and similar absorption for methionine (90%) when compared with the average of all amino acids. Supplementation of these amino acids seems to be viable but it did not result in higher retention compared to the amino acid mix. This means that tryptophan, methionine and arginine are probably not the limiting amino acid when Diplodus sargus larvae are fed rotifers. However, supplementation in these IAA may be required for their roles as precursors of important molecules other than proteins, in order to improve larval quality and/or performance.

Keywords: Keywords: Diplodus sargus – Arginine – Methionine – Tryptophan – Tube-feeding

Discrimination of outer membrane proteins using a K-nearest neighbor method by C. Yan; J. Hu; Y. Wang (pp. 65-73).

Identification of outer membrane proteins (OMPs) from genome is an important task. This paper presents a k-nearest neighbor (K-NN) method for discriminating outer membrane proteins (OMPs). The method makes predictions based on a weighted Euclidean distance that is computed from residue composition. The method achieves 89.1% accuracy with 0.668 MCC (Matthews correlation coefficient) in discriminating OMPs and non-OMPs. The performance of the method is improved by including homologous information into the calculation of residue composition. The final method achieves an accuracy of 96.1%, with 0.873 MCC, 87.5% sensitivity, and 98.2% specificity. Comparisons with multiple recently published methods show that the method proposed in this study outperforms the others.

Keywords: Keywords: Prediction – Transmembrane proteins – Machine learning – Gram-negative bacteria

Hyperactive mutants of mouse d-aspartate oxidase: mutagenesis of the active site residue serine 308 by M. Katane; T. Hanai; T. Furuchi; M. Sekine; H. Homma (pp. 75-82).

The role of Ser-308 of murine d-aspartate oxidase (mDASPO), particularly its side chain hydroxyl group, was investigated through the use of site-specific mutational analysis of Ser-308. Recombinant mDASPO carrying a substitution of Gly, Ala, or Tyr for Ser-308 was generated, and fused to either His (His-mDASPO), or glutathione S-transferase, His, and S (GHS-mDASPO) at its N-terminus. Wild-type His-mDASPO or GHS-mDASPO or their mutant derivatives were expressed in Escherichia coli and purified by affinity chromatography. All purified recombinant proteins had functional DASPO activity. The Gly-308 and Ala-308 mutants had significantly higher catalytic efficiency towards d-Asp and N-methyl-d-Asp, and a higher affinity for flavin adenine dinucleotide (FAD) compared to the wild-type enzyme. The Tyr-308 mutant had lower catalytic efficiency and binding capacity. These results suggest that the side chain hydroxyl group of a critical residue of mDASPO, Ser-308, down-regulates enzymatic activity, substrate binding, and FAD binding. This study provides information on the active site of DASPO that will considerably enhance our understanding of the biological significance of this enzyme.

Keywords: Keywords: d-aspartate oxidase – Flavoprotein – Site-directed mutagenesis – d-amino acid oxidase – d-amino acid – d-aspartate

Synthesis of C₃-symmetric and C₄-symmetric amino acid derivatives via Suzuki–Miyaura cross-coupling reaction by S. Kotha; V. R. Shah (pp. 83-88).

Various non-natural C₃- and C₄-symmetric α-amino acid derivatives have been synthesized via Suzuki–Miyaura cross-coupling reaction between aromatic iodides or bromide and a suitably protected DL-4-boronophenylalanine derivative.

Keywords: Keywords: C₃-Symmetric amino acids – C₄-Symmetric amino acid – Carbon–carbon bond – Non-natural α-amino acid derivatives – Suzuki–Miyaura cross-coupling reaction

Post exercise carbohydrate–protein supplementation: phosphorylation of muscle proteins involved in glycogen synthesis and protein translation by J. L. Ivy; Z. Ding; H. Hwang; L. C. Cialdella-Kam; P. J. Morrison (pp. 89-97).

The enzymes Akt, mTOR, p70^S6K, rpS6, GSK3, and glycogen synthase interact in the control of protein and/or glycogen synthesis in skeletal muscle, and each has been found to respond to exercise and nutrient supplementation. In the present study, we tested the hypothesis that nutrient supplementation post exercise, in the form of a carbohydrate–protein (CHO–PRO) supplement, would alter the phosphorylation state of these enzymes in a manner that should increase muscle protein and glycogen synthesis above that produced by exercise alone. After a 45 min cycling session followed by sprints and again 15 min later, the subjects (n = 8) ingested 400 ml of a CHO–PRO drink (7.8% dextrose and 1.8% protein-electrolyte) or a placebo drink, as assigned using a randomized, counter-balanced design with repeated measures. Biopsies of the vastus lateralis were taken before exercise and at 45 min of recovery. At 45 min after supplementation, CHO–PRO treatment yielded greater phosphorylation of Akt (65%), mTOR (86%), rpS6 (85-fold), and GSK3α/β (57%) than pre-exercise levels (p < 0.05). Although p70^S6k showed an exercise response after 45 min, there were no differences between treatments. Glycogen synthase (GS) phosphorylation was significantly reduced 45 min after exercise for both treatments, but the reduction in phosphorylation was greatest during the CHO–PRO treatment (3-fold decrease; p < 0.05), indicating greater activation of GS following supplementation. No difference between treatments was detected prior to exercise for any of the enzymes. These results suggest that a post exercise CHO–PRO supplement alters the phosporylation levels of the enzymes tested in a manner that should accelerate muscle glycogen synthesis and protein initiation during recovery from cycling exercise.

Keywords: Keywords: Akt – mTOR – p70^S6k – rpS6 – Glycogen – Protein synthesis

Effect of strength training session on plasma amino acid concentration following oral ingestion of arginine or taurine in men by A. Mero; A. Leikas; N. Rinkinen; P. Huhta; J. J. Hulmi; H. Pitkänen; J. Knuutinen (pp. 99-106).

This study examined the acute effects of a one-hour hypertrophic strength training session (STS) on plasma amino acid concentration following oral ingestion of arginine or taurine in nine physically active men participating in a double-blind and randomised experiment. The subjects took placebo, arginine or taurine capsules (50 mg/kg) in either rest (REST) or STS condition. Blood samples were taken before and at 30, 60, 90, and 120 min after the beginning of the treatment and assayed for plasma amino acids with HPLC. There was a significant interaction effect with STS and sample time for both arginine and taurine in the raw data (p < 0.05). The modelled polynomial data for the arginine treatment showed that the peak concentration of arginine occurred at 69 min at rest and at 104 min in STS, and for the taurine treatment, the peak concentration of taurine occurred at 89 min at rest and at 112 min in STS. In conclusion, one hour of hypertrophic STS slows the increase in the peak concentration of plasma arginine and taurine after oral ingestion of the respective amino acids.

Keywords: Keywords: Strength training session – Amino acids – Insulin – Glucose

Central l-arginine reduced stress responses are mediated by l-ornithine in neonatal chicks by R. Suenaga; H. Yamane; S. Tomonaga; M. Asechi; N. Adachi; Y. Tsuneyoshi; I. Kurauchi; H. Sato; D. M. Denbow; M. Furuse (pp. 107-113).

Recently, we observed that central administration of l-arginine attenuated stress responses in neonatal chicks, but the contribution of nitric oxide (NO) to this response was minimal. The sedative and hypnotic effects of l-arginine may be due to l-arginine itself and/or its metabolites, excluding NO. To clarify the mechanism, the effect of intracerebroventricular (i.c.v.) injection of l-arginine metabolites on behavior under social separation stress was investigated. The i.c.v. injection of agmatine, a guanidino metabolite of l-arginine, had no effect during a 10 min behavioral test. In contrast, the i.c.v. injection of l-ornithine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior. The l-ornithine concentration in the telencephalon and diencephalon increased following the i.c.v. injection of l-arginine. In addition, several free amino acids including L-alanine, glycine, l-proline and l-glutamic acid concentrations increased in the telencephalon. In conclusion, it appears that l-ornithine, produced by arginase from l-arginine in the brain, plays an important role in the sedative and hypnotic effects of l-arginine observed during a stress response. In addition, several other amino acids having a sedative effect might partly participate in the sedative and hypnotic effects of l-arginine.

Keywords: Keywords: l-Ornithine – l-Arginine – Agmatine – Intracerebroventricular injection – Social separation stress – Neonatal chick

Differential proteomic analysis of HeLa cells treated with Honokiol using a quantitative proteomic strategy by B. Ling; S.-F. Liang; Y.-H. Xu; X.-Y. Zhao; M.-H. Tang; X.-Y. Liu; X. Zhao; C.-H. Huang; L.-J. Chen; Y.-Q. Wei (pp. 115-122).

Honokiol (HNK) is an active component purified from Magnolia officinalis. HNK exhibits antitumor effects by inducing apoptosis and inhibiting the growth of many cancer cell lines, while proteins involved in antitumor effects in proteomic level are still unclear. In our study, HNK could inhibit HeLa cell proliferation and induce apoptosis in a concentration- and time-dependent manner. We utilized a quantitative proteomic technique termed SILAC (Stable isotope labeling with amino acids in cell culture)-MS (mass spectrometry) to study the differential proteomic profiling of HeLa cells treated by HNK. A total of 85 proteins were changed after HeLa cells were treated with 12 µg/ml HNK for 8 h, and 8 proteins showed up-regulation while 77 proteins down-regulated. The changed proteins were classified into 9 different categories, which covered a broad variety of cellular functions. In conclusion, HNK performs cytotoxicity to HeLa cells through co-operating of many proteins and different pathways.

Keywords: Keywords: Honokiol – Stable isotope labeling with amino acids in cell culture (SILAC) – Differential proteomic profile – HeLa cells

Recombinant tissue metalloproteinase inhibitor-3 protein induces apoptosis of murine osteoblast MC3T3-E1 by L.-Q. Yuan; Y.-S. Liu; X.-H. Luo; L.-J. Guo; H. Xie; Y. Lu; X.-P. Wu; E.-Y. Liao (pp. 123-127).

Tissue inhibitor of metalloproteinases (TIMPs) plays an essential role in the regulation of bone metabolism. Here we report that recombinant tissue metalloproteinase inhibitor-3 (TIMP-3) protein induces the apoptosis of MC3T3-E1 osteoblasts. Cell apoptosis was detected by sandwich-enzyme-immunoassay. Fas and Fasl protein levels were determined by Western blot analysis. The enzyme substrate was used to assess the activation of caspase-3 and caspase-8. The phosphorylation of JNK, p38 and ERK1/2 was examined by Western blot analysis. The ELISA suggested that TIMP-3 promoted MC3T3-E1 cell apoptosis. TIMP-3 treatment induced the expression of Fas and Fasl proteins, and the activation of caspase-8 and caspase-3. TIMP-3 treatment induced p38 and ERK phosphorylation. SB203580 and PD98059, the inhibitor of p38 and ERK, respectively, abolished the TIMP-3 effect on osteoblast apoptosis. In conclusion, the signal pathway through which TIMP-3 induces MC3T3-E1 cell apoptosis, mediated by Fas and involves the p38 and ERK signal transduction pathways.

Keywords: Keywords: Tissue metalloproteinase inhibitor-3 – Osteoblast – Apoptosis

Cloning and functional characterization of the HRASLS2 gene by R.-Y. Shyu; Y.-C. Hsieh; F.-M. Tsai; C.-C. Wu; S.-Y. Jiang (pp. 129-137).

The HRAS-like suppressor 2 (HRASLS2) gene belongs to the H-REV107 gene family involved in the regulation of cell growth and differentiation. HRASLS2 is expressed at high levels in normal tissues of the small intestine, kidney, and trachea. We cloned HRASLS2 cDNA from human SW480 colon cancer cells. Most wild-type, and some N- and C-terminal truncated HRASLS2 (HRASLS2ΔNΔC) were expressed as a granular pattern located at perinuclear region in HtTA cervical cancer cells, while truncation at the C-terminus only (HRASLS2ΔC) resulted in a diffuse pattern. Wild-type HRASLS2 significantly suppressed colony formation of HeLa and HCT116 cells. HRASLS2ΔNΔC significantly inhibited colony formation of HCT116 cells, but HRASLS2ΔC did not affect cell growth. HRASLS2 suppressed the RAS-GTP levels and total RAS protein by 44% and 25%, respectively in HtTA cells; however, the suppression was not observed in truncated HRASLS2 variants. In conclusion, the HRASLS2 protein suppressed growth and RAS activities of cancer cells, and the C-terminal hydrophobic domain appeared to be indispensable for both activities.

Keywords: Keywords: HRASLS2 – Growth suppression – RAS – Tumor suppressor gene – Apoptosis – RARRES3 – HRASLS3

Intracerebroventricular injection of l-arginine induces sedative and hypnotic effects under an acute stress in neonatal chicks by R. Suenaga; S. Tomonaga; H. Yamane; I. Kurauchi; Y. Tsuneyoshi; H. Sato; D. M. Denbow; M. Furuse (pp. 139-146).

l-Arginine participates in many important and diverse biochemical reactions associated with the normal physiology of the organism. In the present study, we investigated the effect of central administration of l-arginine on the stress response and its mechanism in neonatal chicks. Intracerebroventricular (i.c.v.) injection of l-arginine clearly attenuated the stress response in a dose-dependent manner, and induced sleep-like behavior during 10 min. To clarify the mechanism by which l-arginine induces sedative and hypnotic effects in chicks, we investigated the effects of nitric oxide (NO) synthase (NOS) inhibitors on l-arginine-induced sedative and hypnotic effects, and as well as the effects of a NO donor. l-Arginine-induced (1.9 µmol) sedative and hypnotic effects were attenuated by i.c.v. co-injection with a non-selective NOS inhibitor N^G-nitro-l-arginine methyl ester HCl (400 nmol). In addition, the effects of l-arginine were slightly attenuated by the inactive isomer of the NOS inhibitor N^G-nitro-d-arginine methyl ester HCl (400 nmol). The i.c.v. injection of 3-morpholinosylnomine hydrochloride, a spontaneous NO donor, had little effect on postures. The i.c.v. injection of l-arginine had no effect on NOx concentration at various brain sites. These results suggested that the contribution of NO generation via NOS may be low in the sedative and hypnotic actions of l-arginine. Therefore, l-arginine and/or its metabolites, excluding NO, may be necessary for these actions.

Keywords: Keywords: l-Arginine – L-NAME – D-NAME – SIN-1 – Nitric oxide – Intracerebroventricular injection – Social separation stress – Neonatal chick

Antagonistic effects of leucine and glutamine on the mTOR pathway in myogenic C₂C₁₂ cells by L. Deldicque; C. Sanchez Canedo; S. Horman; I. De Potter; L. Bertrand; L. Hue; M. Francaux (pp. 147-155).

This study compared the effects of leucine and glutamine on the mTOR pathway, on protein synthesis and on muscle-specific gene expression in myogenic C₂C₁₂ cells. Leucine increased the phosphorylation state of mTOR, on both Ser2448 and Ser2481, and its downstream effectors, p70^S6k, S6 and 4E-BP1. By contrast, glutamine decreased the phosphorylation state of mTOR on Ser2448, p70^S6k and 4E-BP1, but did not modify the phosphorylation state of mTOR on Ser2481 and S6. Whilst the phosphorylation state of the mTOR pathway is usually related to protein synthesis, the incorporation of labelled methionine/cysteine was only transiently modified by leucine and was unaltered by glutamine. However, these two amino acids affected the mRNA levels of desmin, myogenin and myosin heavy chain in a time-dependant manner. In conclusion, leucine and glutamine have opposite effects on the mTOR pathway. Moreover, they induce modification of muscle-specific gene expression, unrelated to their effects on the mTOR/p70^S6k pathway.

Keywords: Keywords: Amino acids – p70^S6k – 4E-BP1 – protein synthesis – gene expression

Altered pre-pulse inhibition in adult rats treated neonatally with domoic acid by A. L. Adams; T. A. Doucette; C. L. Ryan (pp. 157-160).

Altered functioning of the glutamate system during critical periods of development is believed to play a role in various neurodevelopmental disorders, such as schizophrenia. Prepulse inhibition (PPI) of the acoustic startle response is deficient in people with schizophrenia. This study investigated the theory that neonatal treatment with domoic acid (DOM), a glutamate agonist, leads to deficient PPI. Results indicate that neonatal treatment with DOM leads to lowered PPI in adult males and an increased startle response in adult females.

Keywords: Keywords: Kainate receptors – Glutamate – Brain development – Pre-pulse inhibition – Schizophrenia

Comparison of taurine biosynthesis ability between juveniles of Japanese flounder and common carp by S.-K. Kim; H. Matsunari; T. Takeuchi; M. Yokoyama; H. Furuita; Y. Murata; T. Goto (pp. 161-168).

This study was conducted to investigate taurine deficiency and the ability of taurine biosynthesis in both juvenile Japanese flounder (JF) and juvenile common carp (CC) in vivo using low taurine level diets. Three different taurine level diets were prepared by the supplementation of taurine to the basal composition (JF – 0, 0.5 and 1.5% in JF; CC – 0, 1, 3% in CC). The final average body weight and feed efficiency of JF fed the JF – 1.5% was significantly higher than those of fish fed on the JF – 0%. On the other hand, no significant difference was observed in CC fed with CC – 0, 1, and 3% diets. The taurine retention rate was negative in the case of JF-fed with the taurine-free supplement (JF – 0%). On the other hand, the taurine retention rate was about 280% in the case of CC-fed with the taurine-free supplement (CC – 0%). These findings indicate that while taurine is essential for growth of JF, it is not essential for the growth of CC.

Keywords: Keywords: Taurine-biosynthesis-juvenile – Paralichthys olivaceus – Cyprinus carpio

Design and synthesis of a novel anthracene-based fluorescent probe through the application of the Suzuki–Miyaura cross-coupling reaction by S. Kotha; V. R. Shah; P. P. Mishra; A. Datta (pp. 169-173).

We report on a simple synthetic route to a novel anthracene-based bis-armed amino acid derivative as a useful fluorescent probe. Various photophysical studies of this amino acid derivative are also described. Here, Suzuki–Miyaura cross-coupling reaction has been used as a key step for carbon–carbon bond formation.

Keywords: Keywords: Bis-armed amino acid – Carbon–carbon bond formation – Cross-coupling – Fluorescent amino acid

Thiazolinium and imidazolium chiral ionic liquids derived from natural amino acid derivatives by D. Brégeon; J. Levillain; F. Guillen; J.-C. Plaquevent; A.-C. Gaumont (pp. 175-184).

Starting from commercially available amino acid derivatives, two novel families of chiral ionic liquids having either a thiazolinium or an imidazolium cation were prepared by simple and straightforward procedures in good overall yields. The properties of these new salts can be finely tuned by careful selection of the anion and the cation.

Keywords: Keywords: Amino acid derivatives – Chiral ionic liquids – Thiazolinium salts – Imidazolium salts

Novel chloroenyne-modified amino acid derivatives by M. Gredičak; A. Kolonić; I. Jerić (pp. 185-194).

Three groups of chloroenyne-modified amino acids were synthesized. Chloroenyne moiety was attached at the N- or C-terminal amino acid (Tyr, Phe, Val, Gly, Lys) position carrying different protecting groups. Prepared derivatives will be used as building blocks in the synthesis of enediyne-peptide conjugates. Furthermore, reactivity of modified amino acids in the peptide bond formation reaction was tested.

Keywords: Keywords: Amino acid modifications – Sonogashira reaction – Enediynes – Chloroenynes

Characterisation of the barrier caused by luminally secreted gastro-intestinal proteolytic enzymes for two novel cystine-knot microproteins by M. Werle; H. Kolmar; R. Albrecht; A. Bernkop-Schnürch (pp. 195-200).

It was the aim of this study to evaluate the stability of two novel cystine-knot microproteins (CKM) SE-ET-TP-020 and SE-MC-TR-020 with potential clinical relevance towards luminally secreted proteases of the gastrointestinal tract in order to gain information about their potential for oral administration. Therefore, the stability of the two CKM and the model-drug insulin towards collected porcine gastric and small intestinal juice as well as towards isolated proteolytic enzymes was evaluated under physiological conditions. No intact SE-ET-EP-020 was detected after few seconds of incubation with porcine small intestinal juice. SE-ET-TP-020 was also degraded in porcine gastric juice. Furthermore, SE-ET-TP-020 was extensively degraded by isolated chymotrypsin, trypsin and pepsin. Moreover, it was degraded by elastase. SE-MC-TR-020 was degraded entirely within approximately 2 h when incubated in porcine small intestinal juice, whereas no degradation was observed within a 3 h incubation period with porcine gastric juice. In presence of the isolated proteolytic enzymes, SE-MC-TR-020 was only slightly degraded by trypsin and pepsin, whereas elastase caused no degradation to SE-MC-TR-020 at all. Chymotrypsin was the protease that caused most degradation to SE-MC-TR-020. The model drug insulin was degraded extensively by chymotrypsin, elastase, pepsin and trypsin as well as by porcine gastric and porcine small intestinal juice. In conclusion, a precise characterisation of SE-ET-TP-020 and SE-MC-TR-020 degrading luminally secreted GI enzymes has been made, which is an important and substantial prerequisite for the further optimisation of these CKM.

Keywords: Keywords: Cystine-knot microproteins – CKM – Oral delivery – Enzymatic degradation

Singlet molecular oxygen [O₂(¹Δ_g)]-mediated photodegradation of tyrosine derivatives in the presence of cationic and neutral micellar systems by S. Criado; J. P. Escalada; A. Pajares; N. A. García (pp. 201-208).

The kinetics of rose bengal-sensitized photooxidation of tyrosine and several tyrosine-derivatives (tyr-D) named tyrosine methyl ester, tyrosine ethyl ester and tyrosine benzyl ester was studied in buffered pH 11 water, and buffered pH 11 micellar aqueous solutions of 0.01 M cetyltrimethylammonium chloride (CTAC) and 0.01 M-octylphenoxypolyethoxyethanol [triton X100 (TX100)]. Through time-resolved phosphorescence detection of singlet molecular oxygen (O₂(¹Δ_g)) and polarographic determination of oxygen consumption, the respective bimolecular rate constants for reactive (k_r) and overall (k_t) quenching of the oxidative species by tyr-D were evaluated. Both rate constants behave in different fashion depending on the particular reaction medium. k_r/k_t values, increase in the sense CTAC≪TX100 < water, indicating, for the tyr-D family studied, an excellent degree of self-protection against O₂(¹Δ_g)-attack in the CTAC micellar system and a high photooxidability level in water. Results were interpreted in terms of a competition between solvent polarity effects, local substrate concentration and electron donating capabilities of the substrates in the different media that can contribute to predict the extent of photodynamic damage in biological environments.

Keywords: Keywords: CTAC – Micelles – Photooxidation – Singlet molecular oxygen – Tyrosine – Tyrosine-derivatives – Triton X100

Mapping the human proteome for non-redundant peptide islands by G. Capone; A. De Marinis; S. Simone; A. Kusalik; D. Kanduc (pp. 209-216).

We describe immune-proteome structures using libraries of protein fragments that define a structural immunological alphabet. We propose and validate such an alphabet as i) composed of letters of five consecutive amino acids, pentapeptide units being sufficient minimal antigenic determinants in a protein, and ii) characterized by low-similarity to human proteins, so representing structures unknown to the host and potentially able to evoke an immune response. In this context, we have thoroughly sifted through the entire human proteome searching for non-redundant protein motifs. Here, for the first time, a complete sequence redundancy dissection of the human proteome has been conducted. The non-redundant peptide islands in the human proteome have been quantified and catalogued according to the amino acid length. The library of uniquely occurring n-peptide sequences that was obtained is characterized by a logarithmic decrease of the number of non-redundant peptides as a function of the peptide length. This library represents a highly specific catalogue of molecular protein signatures, the possible use of which in cancer/autoimmunity research is discussed, with a major focus on non-redundant dodecamer sequences.

Keywords: Keywords: Human proteome – Redundant peptide sequences – Quantitative proteomic redundancy – Qualitative proteomic redundancy

Attenuation by dietary taurine of dextran sulfate sodium-induced colitis in mice and of THP-1-induced damage to intestinal Caco-2 cell monolayers by Z. Zhao; H. Satsu; M. Fujisawa; M. Hori; Y. Ishimoto; M. Totsuka; A. Nambu; S. Kakuta; H. Ozaki; M. Shimizu (pp. 217-224).

The effects of dietary taurine on the experimental colitis induced by dextran sulfate sodium (DSS) in mice were evaluated. C57BL/6 female mice were given 3% DSS in drinking water for 5 d to induce acute colitis. Taurine at 2% was added to the drinking water 5 d before and during the DSS-treatment to investigate its preventive effect. Taurine supplementation significantly attenuated the weight decrease, diarrhea severity, colon shortening, and the increase in the colonic tissue myeloperoxidase activity induced by DSS. Taurine also significantly inhibited the increase in the expression of a pro-inflammatory chemokine, macrophage inflammatory protein 2 (MIP-2), but not of interleukin (IL)-1β or tumor necrosis factor (TNF)-α mRNA. Furthermore, taurine significantly protected the intestinal Caco-2 cell monolayers from the damage by macrophage-like THP-1 cells in an in vitro coculture system. These results suggest that taurine prevented DSS-induced colitis partly in association with (1) its inhibitory effects on the secretion of MIP-2 from the intestinal epithelial cells and on the infiltration of such inflammatory cells as neutrophils and (2) its cytoprotective functions on the epithelial barrier from the direct toxicity of DSS and from the inflammatory cell-induced injury.

Keywords: Keywords: Taurine – IBD – DSS – Caco-2 – Colitis

Serum amino acid profile in patients with acute pancreatitis by P. Sandstrom; L. Trulsson; T. Gasslander; T. Sundqvist; U. von Dobeln; J. Svanvik (pp. 225-231).

Patients in the early phase of acute pancreatitis (AP) have reduced serum levels of arginine and citrulline. This may be of patho-biological importance, since arginine is the substrate for nitric oxide, which in turn is involved in normal pancreatic physiology and in the inflammatory process. Serum amino acid spectrum was measured daily for five days and after recovery six weeks later in 19 patients admitted to the hospital for acute pancreatitis. These patients had abnormal levels of most amino acids including arginine, citrulline, glutamine and glutamate. Phenylalanine and glutamate were increased, while arginine, citrulline, ornithine and glutamine were decreased compared to levels after recovery. NO₂/NO₃ concentration in the urine, but not serum arginase activity, was significantly increased day 1 compared to day 5 after admission. Acute pancreatitis causes a disturbance of the serum amino acid spectrum, with possible implications for the inflammatory process and organ function both in the pancreas and the gut. Supplementation of selected amino acids could possibly be of value in this severe condition.

Keywords: Keywords: Pancreas – Acute pancreatitis – Nitric oxide – L-arginine – L-citrulline

Correlation of in vitro and in vivo models for the oral absorption of peptide drugs by F. Föger; A. Kopf; B. Loretz; K. Albrecht; A. Bernkop-Schnürch (pp. 233-241).

The aim of this study was to evaluate two in vitro models, Caco-2 monolayer and rat intestinal mucosa, regarding their linear correlation with in vivo bioavailability data of therapeutic peptide drugs after oral administration in rat and human. Furthermore the impact of molecular mass (Mm) of the according peptides on their permeability was evaluated.Transport experiments with commercially available water soluble peptide drugs were conducted using Caco-2 cell monolayer grown on transwell filter membranes and with freshly excised rat intestinal mucosa mounted in Using type chambers. Apparent permeability coefficients (P _app) were calculated and compared with in vivo data derived from the literature.It was shown that, besides a few exceptions, the Mm of peptides linearly correlates with permeability across rat intestinal mucosa (R ² = 0.86; y = −196.22x + 1354.24), with rat oral bioavailability (R ² = 0.64; y = −401.90x + 1268.86) as well as with human oral bioavailability (R ² = 0.91; y = −359.43x + 1103.83). Furthermore it was shown that P _app values of investigated hydrophilic peptides across Caco-2 monolayer displayed lower permeability than across rat intestinal mucosa. A correlation between P _app values across rat intestinal mucosa and in vivo oral bioavailability in human (R ² = 0.98; y = 2.11x + 0.34) attests the rat in vitro model to be a very useful prediction model for human oral bioavailability of hydrophilic peptide drugs.Presented correlations encourage the use of the rat in vitro model for the prediction of human oral bioavailabilities of hydrophilic peptide drugs.

Keywords: Keywords: Peptides – Oral drug delivery – In vitro in vivo correlation – Caco-2 – Rat intestinal mucosa

Neutrophil fatty acid composition: effect of a single session of exercise and glutamine supplementation by C. J. Lagranha; T. C. Alba-Loureiro; E. F. Martins; T. C. Pithon-Curi; R. Curi (pp. 243-245).

The fatty acid composition of immune cells appears to contribute to variations of cell function. The independent and combined effects of a single session of exercise (SSE) and glutamine supplementation (GS) on neutrophil fatty acid composition were investigated. Compared to control (no treatment given – i.e. neither SSE or GS), single session of exercise decreased myristic, palmitic and eicosapentaenoic (EPA) acids, and increased lauric, oleic, linoleic, arachidonic (AA) and docosahexaenoic (DHA) acids whereas glutamine supplementation combined with SSE (GS+SSE) increased oleic acid. Polyunsaturated/saturated fatty acid ratio and Unsaturation index were higher in neutrophils from the SSE and GS groups as compared with control. These findings support the proposition that SSE and GS may modulate neutrophil function through alterations in fatty acid composition.

Keywords: Keywords: Fatty acid composition – Neutrophils – Glutamine supplementation – Single session of exercise

Low dose domoic acid in neonatal rats abolishes nicotine induced conditioned place preference during late adolescence by M. A. Burt; C. L. Ryan; T. A. Doucette (pp. 247-249).

In this study, neonatal rats were chronically exposed to low, non-convulsive doses of the kainate receptor agonist domoic acid (DOM), or saline. Later, as adolescents, all animals were tested in a nicotine-induced conditioned place preference (CPP) paradigm. As expected, a nicotine-induced CPP was evident in the adolescent control rats, but surprisingly, not in the DOM animals. This study demonstrates the importance of KA receptors in the development of normal adolescent behaviors manifested in response to the rewarding properties of nicotine.

Keywords: Keywords: Kainate receptors – Reward behaviour – Brain development – Mesocorticolimbic pathway – Addiction

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.35, #1)