Check out our New Publishers' Select for Free Articles

Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.17, #2)

Clonidine action in spontaneously hypertensive rats (SHR) depends on the GABAergic system function by B. Goźlińska; Prof. H. Czyżewska-Szafran (pp. 131-138).

The effect of γ-aminobutyric acid (GABA)_A antagonists (bicuculline, picrotoxin) on clonidine hypotension in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats were examined. The GABA turnover changes after clonidine injection in both strains were also studied. Administration of clonidine alone induced the stronger decrease of systolic blood pressure (SBP) in SHR. Co-dosage of clonidine with these agents reduced its hypotensive effect in dose dependent manner and the effectiveness of both antagonists was higher in SHR. We find that clonidine stimulates GABA synthesis in the hypothalamus and the pons-medulla in both strains but the GABA turnover rate is significantly slower in SHR. Therefore, the differences in inhibitory action of GABAA receptor anatgonists between WKY and SHR rats may be explained by central GABAergic system dysfunction in the hypertension. Our results indicate that the down regulation of the GABAergic system observed in hypertension may be compensated by the action of clonidine.

Keywords: Amino acids; Clonidine; GABA_A receptor antagonists; GABA turnover; SHR; WKY rats

Gender-related differences in polyamine oxidase activity in rat tissues by Dr. M. E. Ferioli; O. Pinotti; L. Pirona (pp. 139-148).

Variations in level of polyamines and their related enzymes are frequently observed in response to some treatments which affect in a different way male and female. The possibility of a gender-related difference in the oxidation of polyamines was investigated in rats by measuring the activity of polyamine oxidase, a ubiquitous enzyme of vertebrate tissues, which transforms spermine into spermidine and spermidine into putrescine. The study was carried out on thymus, spleen, kidney and liver of young rats of both sexes, and female rats showed a lower polyamine oxidase activity than male rats in all the tissues. We also found higher values of spermidine acetylation in female than male rats in thymus and liver. Owing to these gender-related differences, a higher spermidine N-acetyltransferase/ polyamine oxidase ratio was found in female than in male rats. A second gender-related difference was a higher spermidine/spermine ratio in female than in male, the only exception being the thymus. These basal differences possibly account for the gender-related differences of polyamine metabolic enzyme activities in response to some treatments, including drugs or hormones.

Keywords: Amino acids; Polyamine oxidase; Polyamines; Gender; Rat

Synthesis of biheterocyclicα-amino acids by S. Achamlale; A. Elachgar; Prof. A. El Hallaoui; A. Alamil; S. Elhajji; M. L. Roumestant; Ph. Viallefont (pp. 149-163).

We report here the synthesis of biheterocyclicα-amino acids by 1,3 dipolar cycloaddition of acetylenic compounds onα-azidoα-amino esters.

Keywords: α-Amino acids; Triazole; Tetrazole; Azide; Alcyne; Cycloaddition

Effect of some herbicides on the production of lysine byAzotobacter chroococcum by J. González-López; M. V. Martínez-Toledo; B. Rodelas; V. Salmerón (pp. 165-173).

Production of lysine byAzotobacter chroococcum strain H23 was studied in chemically-defined media amended with different concentrations of alachlor, metolachlor, 2,4-D, 2,4,5-T and 2,3,6-TBA. The presence of 5, 10, and 50μg/ml of alachlor or 2,3,6-TBA significantly decreased quantitative production of lysine. However, the presence 2,4-D or 2,4,5-T at concentrations of 10 and 50μg/ml enhanced the production of lysine. Quantitative production of lysine was not affected as consequence of the addition of metolachlor to the culture medium, showing that the release lysine to the culture media byA. chroococcum was not affected by that herbicide.

Keywords: Amino acids; Lysine; Herbicides; Azotobacter ; Xenobiotics

Synthesis and enzymology of modifiedN-benzyloxycarbonyl-L-cysteinylglycyl-3,3-dimethylaminopropylamide disulphides as alternative substrates for trypanothione reductase fromTrypanosoma crud: Part 3 by C. T. Yuen; J. Garforth; T. Besheya; R. Jaouhari; J. H. McKie; A. H. Fairlamb; Prof. K. T. Douglas (pp. 175-183).

Kinetic data for alternative substrates of recombinant trypanothione reductase fromTrypanosoma cruzi were measured for a series ofN-substituted-L-cysteinylglycyl-3-dimethylaminopropylamides, in which the cysteineN-substituent was either a variant of the benzyloxycarbonyl group or was L-phenylalanine or L-tryptophan. Replacing the benzylic ether oxygen atom by CH₂. or NH had relatively minor effects on k_cat, but raised the value of K_m, 4.5- and 10-fold, respectively. Similarly, relative to the carbobenzoxy group, anN-L-phenylalanyl orN-L-tryptophanyl replacement on the cysteine hardly altered k_cat, but increased K_m, values by 16.6 and 7.4 fold, respectively. These observations were consistent with the K_m, values referring primarily to binding for this series of nonspecific substrates.

Keywords: Amino acids; Trypanothione; Glutathione; Benzyloxycarbonyl-reductase; Hydrocinnamoyl

Utilization ofd-amino acids byFusobacterium nucleatum andFusobacterium varium by M. Ramezani; S. E. MacIntosh; Dr. R. L. White (pp. 185-193).

The utilization ofd- andl -amino acids with acidic, basic or polar side chains was demonstrated by HPLC. Two species of the anaerobeFusobacterium utilized D-lysine and the L isomers of glutamate, glutamine, histidine, lysine and serine. OnlyF. varium usedl-arginine,d-glutamate andd-serine as substrates, whereasF. nucleatum specifically utilizedd-histidine andd-glutamine.d-Glutamate accumulated in F. nucleatum cultures supplemented withd-glutamine, and ornithine was detected when eitherdl- orl-arginine was included inF. varium cultures. Based on literature precedents,d-glutamate andd-histidine are isomerized to their L isomers prior to degradation, but separate catabolic pathways are possible for each enantiomer of lysine and serine.

Keywords: Amino acids; Anaerobic bacteria; Catabolism; HPLC; Stereochemistry

Amino acids and osmolarity in honeybee drone haemolymph by Dr. B. Leonhard; K. Crailsheim (pp. 195-205).

In the haemolymph of honeybee drones, concentrations of free amino acids were higher than in worker haemolymph, with different relative proportions of individual amino acids. The overall concentration of free amino acids reached its highest level at the 5th day after adult drone emergence, and after the 9^th day only minor changes in the concentration and distribution of free amino acids were observed. This coincides with the age when drones reach sexual maturity and change their feeding behaviour. Levels of essential free amino acids were high during the first 3 days of life and thereafter decreased. Osmolarity was lowest at emergence (334 ± 41 mOsm), increased until the age of 3 days (423 ± 32mOsm) and then stayed generally constant until the 16^th day of life. Only 25-day-old drones had significantly higher osmolarity (532 ± 38 mOsm). The overall change in osmolarity during a drone's lifetime was about 40%.

Keywords: Amino acids; Apis mellifera; Drones; Osmolarity; Age dependency

Evolutionary changes reflected by the cellular amino acid composition by Dr. K. Sorimachi (pp. 207-226).

Comparison of the amino acid composition of cell-proteins using 17 amino acids has been used to investigate the biological evolution of organisms such as bacteria, blue-green alga, green alga, fungi, slime mold, protozoa and vertebrates. The degree of difference in the amino acid ratios between any two groups reflects the degree of divergency in biological evolution. The amino acid composition of the Gram-negative bacteria (Escherichia coli,Klebsiella,Proteus, andVibrio alginolyticus) was identical. However, the amino acid composition ofStaphylococcus aureus andBacillus subtilis, which are Gram-positive bacteria, differed from each other and from the Gram-negative bacteria. The amino acid composition of the blue-green alga (Cyanobacterium,Chroococidiopsis) was quite similar to that ofE. coli. A marked difference in the amino acid composition was observed betweenE. coli and green alga (Chlorella), and significant differences were observed betweenE. coli and other organisms, such as fungi, protozoa (Tetrahymena), slime mold (Dictyostelium discoideum) and vertebrates. In conclusion, the change in cellular amino acid composition reflects the divergence which has occurred during biological evolution, whereas a basic pattern of amino acid composition is maintained in spite of a long period of evolutional divergence among the various organisms. Thus, it is proposed that the primitive life forms established at the end of prebiotic evolution had a similar amino acid composition.

Keywords: Amino acid; Evolution; Procaryotic cell; Eucaryotic cell

Sections

Personal tools

Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.17, #2)

Sections

Personal tools

Local resources

Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.17, #2)