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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.28, #4)

γ-L-glutamyltaurine by S. Bittner; T. Win; R. Gupta (pp. 343-356).

The discovery of the dipeptide γ-glutamyltaurine (γ-GT; glutaurine, Litoralon) in the parathyroid in 1980 and later in the brain of mammals gave rise to studies on intrinsic and synthetic taurine peptides of this type. It was suggested that γ-glutamyltransferase (GGT; γ-glutamyltranspeptidase) in the brain is responsible for the in vivo formation of this unusual dipeptide. γ-GT has been prepared by both synthetic and enzymatic methods. The chemical syntheses included the use of protecting groups and coupling methods. A wide spectrum of analytical and spectroscopic methods was used to confirm the structure of the synthetic compounds and to elucidate the position of the peptide bond. Enzymatic preparation of γ-GT from taurine takes advantage of the selective transpeptidation action of GGT on L-glutamine, glutathione, γ-glutamyl-p-nitroanilide or other glutamine donors. Although the functional roles of γ-GT in the brain are only poorly understood, many of its established CNS effects have been reported in the last 25 years. Its effect on emotional arousal and its anti-conflict potencies are synergistic with the anxiolytic drug diazepam. γ-GT exhibits anti-conflict potency, which is exerted by reducing aversion or phobia and/or the anxiety levels. γ-GT also acts as endogenous modulator in excitatory aminoacidergic neurotransmission. It is suggested that such acidic peptides through N-methyl-D-aspartic acid receptors could be part of the neurochemical substrate underlying self-stimulation of the medial prefrontal cortex. Other γ-GT effects in neural systems include: effects on the monoamine concentration in the brain; effects on aggressive behavior in the cat; effects on thyroid hormones in the rat; amelioration of electroshock-induced amnesia; potent and long-lasting antiepileptic action (on intra-amygdaloid injection); affect the glutamatergic system in schizophrenic disorders. Roles for γ-GT in non-neural systems have also been reported, e.g., effects on the metamorphosis of amphibians; on plasma rennin regulation; on radiation protection; on uric acid levels; on human antibody-dependent cell-mediated cytotoxicity (ADCC) and many more.

Keywords: Keywords: Taurine – γ-Glutamyl taurine – Dipeptide – Neural systems – Non-neural systems

S-Adenosylmethionine and protein methylation by M. A. Grillo; S. Colombatto (pp. 357-362).

The enzymes responsible for protein methylation by S-adenosylmethionine, both at the carboxyl groups and at the nitrogen groups, are reviewed. The possibility that the reactions involved may be reversible is also considered.

Keywords: Keywords: Protein methyltransferases – Isoaspartyl residues – Protein phosphatase 2A – Histones – Isoprenylcysteine

Liberation of amino acids by heterotrophic nitrogen fixing bacteria by J. González-López; B. Rodelas; C. Pozo; V. Salmerón-López; M. V. Martínez-Toledo; V. Salmerón (pp. 363-367).

Large amounts of amino acids are produced by nitrogen-fixing bacteria such as Azotobacter, Azospirillum, Rhizobium, Mesorhizobium and Sinorhizobium when growing in culture media amended with different carbon and nitrogen sources. This kind of bacteria live in close association with plant roots enhanced plant growth mainly as a result of their ability to fix nitrogen, improving shoot and root development suppression of pathogenic bacteria and fungi, and increase of available P concentration. Also, it has been strongly evidenced that production of biologically substances such as amino acids by these rhizobacteria are involved in many of the processes that explain plant-grown promotion. This paper reviews literature concerning amino acids production by nitrogen-fixing bacteria. The role of amino acids in microbial interactions in the rhizosphere and establishment of plant bacterial association is also discussed.

Keywords: Keywords: Amino acids – Azotobacter – Azospirillum – Rhizobium – Mesorhizobium – Sinorhizobium

Synthesis, characteristics and biological activity of pentacoordinated spirophosphoranes derived from amino acids by L. Yu; Z. Liu; H. Fang; Q. L. Zeng; Y. F. Zhao (pp. 369-372).

The reactions of phosphorus trichloride with various amino acids afford the pentacoordinated spirophosphoranes. The reaction procedures were traced by ³¹P NMR spectra techniques. A new crystal structure of alanine derivative was characterized, which is a slightly distorted TBP structure. Besides, this kind of spirophosphoranes are potent inhibitors to tyrosinase.

Keywords: Keywords: Pentacoordinated spirophosphoranes – ³¹P NMR – TBP – Tyrosinase inhibition

Using pseudo amino acid composition to predict protein subcellular location: Approached with Lyapunov index, Bessel function, and Chebyshev filter by Y. Gao; S. Shao; X. Xiao; Y. Ding; Y. Huang; Z. Huang; K.-C. Chou (pp. 373-376).

With the avalanche of new protein sequences we are facing in the post-genomic era, it is vitally important to develop an automated method for fast and accurately determining the subcellular location of uncharacterized proteins. In this article, based on the concept of pseudo amino acid composition (Chou, K.C. Proteins: Structure, Function, and Genetics, 2001, 43: 246–255), three pseudo amino acid components are introduced via Lyapunov index, Bessel function, Chebyshev filter that can be more efficiently used to deal with the chaos and complexity in protein sequences, leading to a higher success rate in predicting protein subcellular location.

Keywords: Keywords: Covariant-discriminant algorithm – Pseudo amino acid composition – Chaos – Lyapunov index – Bessel function – Chebyshev filter

Regional distribution of biogenic amines, amino acids and cholinergic markers in the CNS of the C57BL/6 strain by D. Van Dam; B. Marescau; T. Cremers; J. Mulder; S. Engelborghs; P. P. De Deyn (pp. 377-387).

A reliable extrapolation of neurochemical alterations from a mouse model to human metabolic brain disease requires knowledge of neurotransmitter levels and related compounds in control mouse brain. C57BL/6 is a widely used background strain for knockout and transgenic mouse models. A prerequisite for reliable extrapolation from mouse brain to the human condition is the existence of analogous distribution patterns of neurotransmitters and related compounds in control mouse and human brain. We analysed regional distribution patterns of biogenic amines, neurotransmitter and non-neurotransmitter amino acids, and cholinergic markers. Distribution patterns were compared with known neurotransmitter pathways in human brain. The present study provides a reference work for future analyses of neurotransmitters and related compounds in mouse models bred in a C57BL/6 background strain.

Keywords: Keywords: Amino acids – Biogenic amines – Cholinergic markers – C57BL/6 – Brain – Regional distribution

Determination of asymmetric and symmetric dimethylarginines in plasma of hyperhomocysteinemic subjects by R. Paroni; I. Fermo; P. Fiorina; G. Cighetti (pp. 389-394).

The aim of this study was to investigate the possible relationship among dimethylarginines (asymmetric, ADMA; symmetric, SDMA) and homocysteine (Hcy) levels in subjects affected by chronic, mild to intermediate, hyperhomocysteinemia.ADMA and SDMA were assayed by an optimised HPLC method in 75 patients (Hcy = 20.8 μmol/L, 17.1–30.2; median and percentile range) and, for comparison, in 85 healthy subjects (Hcy = 8.0 μmol/L, 7.0–9.1). In controls, the cut-off values were set at 0.61 μmol/L for ADMA and 0.56 or 0.48 μmol/L for male and female SDMA, respectively. In patients, ADMA and SDMA levels were increased (p<0.001) with respect to controls, but no correlation with Hcy was observed. Hyperhomocysteinemic subjects showed a different behaviour in respect to ADMA and SDMA levels and this allowed their stratification in 3 subgroups characterized by ADMA and SDMA in the normal range, only SDMA, or both ADMA and SDMA over the cut-off values. A lack of correlation with Hcy was again observed, thus minimizing the direct role of Hcy on ADMA and SDMA metabolism and suggesting the need for further studies on this issue.

Keywords: Keywords: Asymmetric dimethylarginine – Symmetric dimethylarginine – Hyperhomocysteinemia – Plasma

Using string kernel to predict signal peptide cleavage site based on subsite coupling model by M. Wang; J. Yang; K.-C. Chou (pp. 395-402).

Owing to the importance of signal peptides for studying the molecular mechanisms of genetic diseases, reprogramming cells for gene therapy, and finding new drugs for healing a specific defect, it is in great demand to develop a fast and accurate method to identify the signal peptides. Introduction of the so-called {−3,−1, +1} coupling model (Chou, K. C.: Protein Engineering, 2001, 14–2, 75–79) has made it possible to take into account the coupling effect among some key subsites and hence can significantly enhance the prediction quality of peptide cleavage site. Based on the subsite coupling model, a kind of string kernels for protein sequence is introduced. Integrating the biologically relevant prior knowledge, the constructed string kernels can thus be used by any kernel-based method. A Support vector machines (SVM) is thus built to predict the cleavage site of signal peptides from the protein sequences. The current approach is compared with the classical weight matrix method. At small false positive ratios, our method outperforms the classical weight matrix method, indicating the current approach may at least serve as a powerful complemental tool to other existing methods for predicting the signal peptide cleavage site.The software that generated the results reported in this paper is available upon requirement, and will appear at http://www.pami.sjtu.edu.cn/wm.

Keywords: Keywords: Signal peptide – Chou’s subsite coupling approach – Probabilistic model – String kernels – Support vector machine

Proteinase 3 hydrolysis of peptides derived from human elastin exon 24 by C. Lombard; D. Bouchu; J. Wallach; J. Saulnier (pp. 403-408).

In normal and pathological tissues, elastin-derived peptides proceed of elastin degradation by polymorphonuclear leukocyte proteases: elastase, cathepsin G and proteinase 3. They were demonstrated to have a chemotactic activity, to promote cell proliferation and protease release, . . .. To be biologically active, their structures, which reflect elastase specificity, must adopt a β-turn conformation which accommodate to the cell surface-located elastin binding protein. In this study, we establish that human elastin exon 24-derived peptides containing at least two repeated VGVAPG sequences are hydrolyzed by the proteinase 3 (Pr3). As shown by mass spectrometry analyses, the demonstrated cleavage sites are in agreement with previously reported Pr3 substrate specificity and its lengthy substrate binding site. The characterization of the Pr3-generated products indicate that they contain at least one GXXPG sequence known to stimulate cellular effects after binding to the elastin receptor.

Keywords: Keywords: Elastin peptides – Exon 24 – Proteinase 3 – Hydrolysis – GVAPGV

Preparation of new amino acid complex nanoparticles of bismuth and leucine by R. R. Jia; C. P. Wu; Y. X. Yang; Y. R. Chen; J. R. Zhang; Y. Q. Jia (pp. 409-412).

The new amino acid complex nanoparticles of bismuth and leucine can be prepared very easily by a room temperature solid–solid reaction. The various characterizations indicate that the formula of the complex is BiCl[(CH₃)₂CHCH₂CHNH₂COO]₂1.5H₂O. The crystal structure of the solid complex belongs to monoclinic system with the lattice parameters: a = 1.6036 nm, b = 1.9903 nm, c = 2.1979 nm and β=108.06°. The new solid complex is nanoparticles with average size about 80 nm.

Keywords: Keywords: Leucine complex of bismuth – Nanoparticles – Room temperature solid–solid reaction preparation

Pseudo-peptides derived from isomannide as potential inhibitors of serine proteases by E. M. F. Muri; M. Gomes Jr.; M. G. Albuquerque; E. F. F. da Cunha; R. B. de Alencastro; J. S. Williamson; O. A. C. Antunes (pp. 413-419).

Hepatitis C, Dengue and West Nile virus are among of the most important flaviviruses that share one important serine protease enzyme. Serine proteases belong to the most studied class of proteolytic enzymes, and are a primary target in the drug development field. In this paper, we describe the synthesis and preliminary molecular modeling studies of a novel class of N-t-Boc amino acid amides derived of isomannide as potential serine proteases inhibitors.

Keywords: Keywords: Flaviviruses – Serine protease – Isomannide

Production of amino acids by Azotobacter vinelandii and Azotobacter chroococcum with phenolic compounds as sole carbon source under diazotrophic and adiazotrophic conditions by J. J. Revillas; B. Rodelas; C. Pozo; M. V. Martínez-Toledo; J. González López (pp. 421-425).

Azotobacter vinelandii strain ATCC 12837 and Azotobacter chroococcum strain H23 (CECT4435) were tested to grow in N-free or NH₄Cl amended chemically defined media, with protocatechuic acid or sodium p-hydroxybenzoate as sole carbon (C) sources at a concentration of 2 mmol/L. Both substrates supported grow at similar rates than bacteria grown in control media amended with 2 mmol/L sodium succinate as C source. The two strains produced aspartic acid, serine, glutamic acid, glycine, hystidine, threonine, arginine, alanine, proline, cysteine, tyrosine, valine, methionine, lysine, isoleucine, leucine and phenylalanine after 72 h of growth in chemically defined media with 2 mmol/L of phenolic compounds or sodium succinate as sole C source amended or unamended with 0.1% (w/v) NH₄Cl. Qualitative and quantitative production of all amino acids was not affected by the use of different C and N substrates.

Keywords: Keywords: Amino acids – Azotobacter – Phenolic compounds – Soil microbiota

Bio-available amino acids extraction from soil by demineralized water and 0.5 M ammonium acetate by P. Formánek; B. Klejdus; V. Vranová (pp. 427-429).

The extraction and comparison of soil bio-available amino acids using either demineralised water (DEMI H₂O) or 0.5 M ammonium acetate (0.5 M AAc) solution is reported. Results show that the extraction by 0.5 M AAc is a better method to assess the concentration of bio-available amino acids in soil than DEMI H₂O due to higher extraction efficiency and better amino acid protection against microbial degradation during processing.

Keywords: Keywords: Soil – Amino acids – Extraction

Analysis of saliva for glutathione and metabolically related thiols by liquid chromatography with ultraviolet detection by E. Bald; R. Głowacki (pp. 431-433).

A method for simultaneous determination of glutathione and its precursors cysteine, cysteinylglycine and homocysteine in saliva is presented. The procedure involves reductive conversion of disulfides to thiols, derivatization to their 2-S-quinolinium derivatives with 2-chloro-1-methylquinolinium tetrafluoroborate and separation and quantitation by reversed-phase ion-pairing high performance liquid chromatography with ultraviolet detection at 355 nm. The calibration performed with saliva samples spiked with thiol disulfides, within the practical concentration ranges, showed linear response of the detector. The method applied to the saliva samples donated by volunteers showed mean concentration (SD, n = 8) of cysteine, cysteinylglycine, glutathione and homocysteine: 26.5 (31.6), 6.05 (5.12), 16.97 (7.68), 3.64 (1.34) nmol/ml respectively.

Keywords: Keywords: Saliva – Cysteine – Cysteinylglycine – Glutathione – Homocysteine – Liquid chromatography

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.28, #4)

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.28, #4)