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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.26, #2)
Taurine concentration in the brain and in the plasma following intraperitoneal injections by F. Lallemand; Ph. De Witte (pp. 111-116).
The effect of different taurine doses (0.050, 0.125, 0.250, 0.500 and 1.000 g/kg) administered intraperitoneally to Wistar rats was studied in both the plasma and the hippocampal microdialysate content.The samples were analyzed by reverse phased HPLC for the microdialysate samples and by HPLC with ion-exchange post-column derivatization (ninhydrin) for the plasma samples.In both plasma and microdialysate, we observed a dose dependent increase of taurine concentration. The AUC curves obtained from both microdialysate and plasma samples showed that the increase of taurine concentrations were linear. The mean ratio between AUC’s microdialysate and plasma was 1.63±0.21 showing thus an unbalance between plasma and brain taurine content; a mechanism which enhance taurine transfer from the plasma to the brain was assumed.
Keywords: Keywords: Taurine – Microdialysis – Plasma – Hippocampus – Rat – HPLC
Ethanol but not acetaldehyde induced changes in brain taurine: a microdialysis study by V. A. Kashkin; P. De Witte (pp. 117-124).
Research has suggested that catalase plays a role in mediating ethanol’s psychopharmacological effects. Catalase is an enzyme that oxidizes ethanol to acetaldehyde. It has been reported that when catalase activity is reduced by 3-amino-1,2,4-triazole (AT), rats reduce their intake and preference for ethanol. The present study assessed the effects of AT on the brain amino acids levels following ethanol administration in Wistar rats. The study consisted of three parts. In the first part, we found no effects of acute and chronic intraperitoneally administered acetaldehyde on amino acids dialysate levels in nucleus accumbens. In the second part, AT was administered five hours prior to ethanol or its vehicle. Ethanol significantly affected the levels of taurine in rat pre-treated with AT. In the final part, ethanol was administered following the pre-treatment with AT but the dependent variable was the concentration of ethanol in the brain.
Keywords: Keywords: 3-Amino-1,2,4- triazole – Ethanol – Acetaldehyde – Microdialysis – Catalase
Free amino acids and biogenic amines in red and white muscle of tuna stored in controlled atmospheres by C. Ruiz-Capillas; A. Moral (pp. 125-132).
This paper analyses the presence of and changes in free amino acids and biogenic amines in red and white muscle of bigeye tuna during storage in controlled atmospheres with 2 gas mixes containing different concentrations of CO2 and O2. Levels of amines were generally higher in white than in red muscle, with the exception of putrescine and spermidine. Levels of biogenic amines increased (p<0.05) throughout storage, commencing later in red than in white muscle. A correlation between the amino acid histidine and the biogenic amine histamine was observed, but only in white muscle. Only in the case of tryptophan did white and red muscle differ (p<0.05) in terms of essential free amino acid content. They also differed in anserine content. Concentrations of the non-essential FAAs glutamic acid, glycine and alanine were higher in red than in white muscle. The effectiveness of the atmospheres was reflected in the evolution of both biogenic amines and FAAs. Gas mix 1, containing a higher concentration of CO2, was the more effective.
Keywords: Keywords: Free amino acids – Histidine – Red and white muscle – Tuna – Controlled atmosphere
Mediated exodus of L-dopa from human epidermal Langerhans cells by B. Falck; N. Bendsoe; G. Ronquist (pp. 133-138).
L-3,4-dihydroxyphenylalanine (L-dopa) is not metabolized within human epidermal Langerhans cells (LC); yet they can take up substantial amounts of this amino acid which subsequently can be released into the extracellular space. We recently reported that human epidermal energy metabolism is predominantly anaerobic and that the influx mechanism is a unidirectional L-dopa/proton counter-transport system and now we describe conditions for the mediated transport of L-dopa out of the LC. It is demonstrated that certain amino acids and one dipeptide can effectively trigger the efflux of L-dopa taken up by the LC.Thus, α-methyl-dopa (α-m-dopa), D-dopa and the dipeptide, met–ala at the outside of the plasma membrane stimulated the efflux of L-dopa from L-dopa loaded LC. Similar effects were achieved by a variety of other amino acids in the extracellular fluid while some other amino acids were inactive. The time required for 50% D-methionine-induced exodus of L-dopa from L-dopa loaded LC was in the range of 5–7 min and a complete exodus of L-dopa was attained at about 20 min of incubation. This dislocation of L-dopa to the extracellular fluid is interpreted as an expression of trans-stimulation. In the case of α-m-dopa, D-dopa and met–ala, which admittedly were not able to penetrate the plasma membrane of LC, the concept of trans-stimulation was given a new purport, since none of them were able to participate in an exchange reaction. Finally, it could be concluded that L-dopa escaped by a route different from the one responsible for L-dopa uptake in LC.Thus, while the influx of L-dopa supports extrusion of protons deriving from anaerobic glycolysis in the LC, L-dopa efflux can provide the cells with useful amino acids in an energy-saving way, altogether a remarkable biological process. From this follows that L-dopa has a biological function of its own, besides being a precursor in the catecholamine and pigment syntheses.
Keywords: Keywords: Amino acid transport – Epidermis – Langerhans cells – L-dopa – Trans-stimulation
Synthesis of novel 3-pyridinecarbonitriles with amino acid function and their fluorescence properties by A. S. Girgis; A. Kalmouch; H. M. Hosni (pp. 139-146).
A variety of N-[(4,6-diaryl-3-pyridinecarbonitrile)-2-yl] amino acid esters 2–4 were synthesized through the reaction of 2-bromo-3-pyridinecarbonitriles 1 with the appropriate α-amino acid ester hydrochloride in refluxing dioxane in the presence of triethylamine as dehydrohalogenating agent. Similarly, N′-glycylglycine analogues 5 were obtained through the reaction of 1 with the dipeptide ester. On the other hand, attempts were made towards the construction of amino acid derivatives 7 through the reaction of 1 with aqueous solution α-amino acids 6 in refluxing pyridine, but were unsuccessful, and instead the unexpected 2-amino-3-pyridinecarbonitriles 8 were isolated. The fluorescence properties of the newly synthesized pyridines 2–5 were evaluated. Some of the prepared compounds show considerable antibacterial activity.
Keywords: Keywords: 3-Pyridinecarbonitriles – α-Amino acids – Aromatic nucleophilic substitution – Fluorescence properties
Comparison of post-translational modifications of alpha A-crystallin from normal and hereditary cataract rats by N. Fujii; N. Takeuchi; N. Fujii; T. Tezuka; K. Kuge; T. Takata; A. Kamei; T. Saito (pp. 147-152).
In order to investigate the relationship between lens opacities and the various modifications of lens proteins, we analyzed and compared the properties of lens proteins of 85-day old normal Wistar rats and the hereditary cataract model, ICR/f rats. The present study identified many differences between normal and mutant lens proteins. In the ICR/f mutant rats, the relative amounts of gamma-crystallin decreased and high molecular weight (HMW) protein increased. Racemization and isomerization of Asp-151 of alpha A-crystallin was observed in the mutant ICR/f rats, and Met-1 of alpha A-crystallin was oxidized to methionine sulfoxide. These modifications were not found in the age-matched normal rats. These tendencies are consistent with aged and cataractous human lenses.
Keywords: Keywords: Aging – Alpha A-crystallin – Cataract – Isomerization – Oxidation – Racemization
Properties of synthetic ferrihydrite as an amino acid adsorbent and a promoter of peptide bond formation by G. Matrajt; D. Blanot (pp. 153-158).
Ferrihydrite, an iron oxide hydroxide, is found in all kinds of environments, from hydrothermal hot springs to extraterrestrial materials. It has been shown that this material is nanoporous, and because of its high surface area, it has outstanding adsorption properties and in some cases catalysis properties. In this work we studied the adsorption properties of ferrihydrite with respect to amino acids. Samples of pure ferrihydrite were synthesised and exposed to solutions of amino acids including both proteinaceous and non-proteinaceous species. These experiments revealed important characteristics of this mineral as both an adsorbent of amino acids and a promoter of peptide bond formation.
Keywords: Keywords: Ferrihydrite – Amino acid adsorption – Peptide bond formation
Protective effect of taurine on the detachment of cultured cardiac fibroblasts from the substratum induced by calcium depletion by M. Azuma; K. Takahashi; A. Kimura; T. Matsuda; S. W. Schaffer; J. Azuma (pp. 159-162).
Removal of Ca2+ from the incubation medium of cultured rat cardiac fibroblasts causes cellular morphological changes, such as the formation of blebs, the ballooning of the cell membrane and the detachment from the culture dish. A 24 hr preincubation with 20 mM taurine blocked the Ca2+ depletion-induced detachment of the cardiac fibroblasts. However, taurine treatment did not prevent other morphological changes induced by Ca2+ depletion. The data suggest that taurine plays an important role in cell adhesion in the heart.
Keywords: Keywords: Taurine – Calcium – Cardiac fibroblasts – Morphological change – Cell adhesion
Cysteine-induced hypoglycemic brain damage: an alternative mechanism to excitotoxicity by V. Gazit; R. Ben-Abraham; R. Coleman; A. Weizman; Y. Katz (pp. 163-168).
Central neural damage caused by L-cysteine (L-Cys) was first reported more than 30 years ago. Nevertheless, the exact mechanisms of L-Cys-mediated neurotoxicity are still unclear. Preliminary study in mice demonstrated that, following L-Cys injection, animals developed tachypnea, tremor, convulsions, and death in conjunction with documented hypoglycemia. The aim of the present study was to further investigate the mechanism of L-Cys-mediated hypoglycemic effect and neural damage. Neonatal ICR mice (n=6) were injected with L-Cys (0.5–1.5 mg/g body weight [BW]), and their blood glucose and insulin levels were determined up to 90 min following the injection. Experiments were repeated in chemically (streptozotocin [STZ]) pancreatectomized animals. Brain histology was assessed. Mice injected with L-Cys exhibited dose-dependent neurotoxicity and higher mortality as compared with controls. L-Cys (1.2–1.5 mg/g BW) caused severe hypoglycemia (glucose<42 mg/dl) (P<0.001). In STZ-treated (diabetic) animals, L-Cys (1.5 mg/g BW) increased plasma insulin levels 2.3-fold and decreased serum glucose levels by 50% (P<0.01). Brain histology revealed destruction of as much as 51% of hippocampal neurons in the L-Cys-treated mice but not in the glucose-resuscitated animals. These findings suggest that L-Cys injection can cause pronounced hypoglycemia and central neural damage which is glucose reversible. Since L-Cys is chemically different from the other excitatory amino acids (glutamate and aspartate), L-Cys-mediated neurotoxicity may be connected to its hypoglycemic effect.
Keywords: Keywords: Excitatory amino acids – Cysteine – Glucose – Brain damage
Threonine is the best substrate for D-lactate formation in octopus tentacle by S. Akagi; S. Ohmori (pp. 169-174).
Carbon sources for D-lactate and enzyme activities related to D-lactate formation were investigated using cell-free homogenates of Octopus vulgaris tentacle tissue. The results are as follows: a) The best precursor for D-lactate formation was threonine and second best precursors were glycine and fructose-1,6-bisphosphate. Threonine and glycine served as precursors only in presence of glutathione. b) Both amino acids were precursors for methylglyoxal from which D-lactate was synthesized. Alanine, cysteine and serine were not precursors. We present a metabolic map for D-lactate formation in octopus in order to explain these experimental results.
Keywords: Keywords: Threonine – Glycine – D-Lactate – Methylglyoxal – Octopus
Novel phenomena in the 13C NMR spectra of amino acids by J. Tian; Y. Yin (pp. 175-181).
13C NMR integral areas and spin-lattice relaxation times (T 1’s) of a series of amino acids were determined at different concentrations. It was found that the spin-lattice relaxation times were markedly reduced in 3 M magnesium chloride resulting in the integral area being proportional to the number of carbon atoms producing each particular signal, with a reliability in excess of 95%. Magnesium chloride is proposed as a 13C NMR relaxation agent for amino acids.
Keywords: Keywords: Amino acids – Magnesium chloride – 13C NMR relaxation agent – Spin-lattice relaxation time
Effects of culture conditions on taurine uptake by various variants of human endometrial carcinoma cells in culture by S. Deret; J. Voegelin; I. H. C. Lelong-Rebel; G. Rebel (pp. 183-195).
The general properties of the taurine uptake in human endometrial tumoral Ishikawa cells were similar to those usually found in other tissues. Uptake was notably affected by the oxygen pressure, being higher at the physiological pO2 of the endometrium (40 mm Hg, equivalent to 5% O2) compared to that used under standard experimental culture conditions (160 mm Hg or 20% O2). Uptake of taurine was also density-dependent in Ishikawa cells and was significantly decreased at confluence. Uptake regulation by PKC driven phosphorylation occurs only in growing cells and not in resting cells. The taurine uptake of three Ishikawa cell lines was very different. The taurine uptake of one of the cell lines was affected by estradiol, probably through a non-genomic pathway, whereas tamoxifen had no effect in all cell lines.
Keywords: Keywords: Taurine uptake – Estradiol – Tamoxifen – Oxygen pressure – Ishikawa cell line
Excitotoxin-induced changes in transglutaminase during differentiation of cerebellar granule cells by D. Caccamo; M. Currò; G. Cusumano; G. Crisafulli; R. Ientile (pp. 197-201).
Excitotoxicity induced by NMDA receptor stimulation is able to increase the activity of many enzymes involved in neuronal cell death. Primary cultures of rat cerebellar granule cells were used to elucidate the role of transglutaminase reaction in the excitotoxic cell response, and to evaluate the role of glutamate receptors in cell survival and degeneration. Granule neurons, maintained in vitro for two weeks, were exposed to NMDA at different stages of differentiation. Following NMDA receptor activation, increases in transglutaminase activity were observed in cell cultures. The levels of enzyme activity were higher in cells at 5 days in vitro than in those at 8–9 or 13–14 days in vitro. Moreover, NMDA exposure up-regulated tTG expression in neurons as young as 5 days in vitro. These cultures also exhibited morphological changes with clear apoptotic features. Results obtained demonstrate that susceptibility of granule cells to excitotoxicity depends on the developmental stage of neurons.
Keywords: Keywords: Transglutaminase – Excitotoxicity – Neurodegenerative diseases – Apoptosis – Glutamate – Cerebellar granule neurons
Role of taurine supplementation to prevent exercise-induced oxidative stress in healthy young men by M. Zhang; I. Izumi; S. Kagamimori; S. Sokejima; T. Yamagami; Z. Liu; B. Qi (pp. 203-207).
To evaluate the protective effects of taurine supplementation on exercise-induced oxidative stress and exercise performance, eleven men aged 18–20 years were selected to participate in two identical bicycle ergometer exercises until exhaustion. Single cell gel assay (SCG assay) was used to study DNA damage in white blood cells (WBC). Pre-supplementation of taurine, a significant negative correlation was found between plasma taurine concentration before exercise and plasma thiobaribituric-acid reactive substance (TBARS) 6 hr after exercise (r=−0.642, p<0.05). WBC showed a significant increase in DNA strand breakage 6 hr and 24 hr after exercise. Seven-day taurine supplementation reduced serum TBARS before exercise (p<0.05) and resulted in a significantly reduced DNA migration 24 hr after exercise (p<0.01). Significant increases were also found in VO2max, exercise time to exhaustion and maximal workload in test with taurine supplementation (p<0.05). After supplementation, the change in taurine concentration showed positive correlations with the changes in exercise time to exhaustion and maximal workload. The results suggest that taurine may attenuate exercise-induced DNA damage and enhance the capacity of exercise due to its cellular protective properties.
Keywords: Keywords:Taurine – DNA damage – Exhaustive exercise – Lipid peroxidation – Antioxidant
N-Acyl derivatives of Asn, new bacterial N-acyl D-amino acids with surfactant activity by F. Peypoux; O. Laprévote; M. Pagadoy; J. Wallach (pp. 209-214).
New N-acyl D-amino acids were isolated from Bacillus pumilus IM 1801. Their structures were determined by chemical analysis and mass spectrometry. The lipid part was identified as a mixture of fatty acids with 11, 12, 13, 15, and 16 carbon atoms in the iso, anteiso or n configuration linked by an amide bond with a D-asparagine. They exhibited surfactant properties.
Keywords: Keywords: N-acyl D-amino acids – Mass spectrometry – Bacillus pumilus – Surfactant activity