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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.18, #2)

Effect of cycloheximide on tryptophan binding to rat hepatic nuclei by H. Sidransky; E. Verney (pp. 103-116).

This study evaluated whether cycloheximide, an inhibitor of protein synthesis, would affect the binding of L-tryptophan to rat hepatic nuclei or nuclear envelopes. Previous reports have indicated that the binding of L-tryptophan to hepatic nuclear envelope protein was saturable, stereospecific, and of high affinity. Also, the administration of L-tryptophan rapidly stimulated hepatic protein synthesis. In this study, we determined that the addition of cycloheximide in vitro inhibited ³H-tryptophan binding to hepatic nuclei or nuclear envelopes. Heat-treated cycloheximide failed to have this inhibitory binding effect. In vivo treatment of rats with cycloheximide diminished in vitro ³H-tryptophan binding to hepatic nuclei of treated rats compared to controls. Puromycin, another inhibitor of hepatic protein synthesis, when added in vitro did not affect ³H-tryptophan binding to hepatic nuclei but did diminish in vitro binding after in vivo treatment. Thus, cycloheximide added in vitro diminished ³H-tryptophan binding to hepatic nuclei probably by its structural effect on the receptor while cycloheximide administered in vivo may also act in part by inhibiting protein synthesis.

Keywords: Keywords: Amino acids – L-tryptophan – Hepatic nuclear binding – Cycloheximide – Rats

Synthesis of conformationally constrained hydroxy-α-amino acids by intramolecular conjugate addition by A. Avenoza; J. H. Busto; C. Cativiela; J. M. Peregrina (pp. 117-127).

An efficient and easily applicable method for the synthesis of a variety of hydroxy-α-amino acids analogues of serine and phenylalanine has been established. The method involves the stereoselective intramolecular conjugate addition of the benzamide group to cyclohexenone promoted by Lewis acid. Subsequent transformations of functional groups pro-vide the conformationally constrained 2-hydroxy- and 2,4-dihydroxy-6-phenylcyclohexane-α-amino acids.

Keywords: Keywords: Amino acids – 5(4H)-Oxazolone – Diels-Alder reaction – Intramolecular conjugate addition – Hydroxy-α-amino acids

Polyamines are unevenly distributed within the rat and rabbit kidney by O. Levillain; R. Havouis; J. P. Moulinoux (pp. 129-137).

Aliphatic polyamines have generally been measured on the whole kidney. Since the kidney is composed of a variety of cells, whole organ data are of limited value for the interpretation of the functions of the polyamines. The aim of this study was to establish the distribution pattern of putrescine, spermidine and spermine within the kidneys of male and female rats and rabbits. It is shown that the polyamines are unevenly distributed along the cortico-papillary axis. Each amine exhibited its own distinct distribution pattern. The polyamines are predominantly located in the cortex. Putrescine levels increased gradually from the cortex to the papillary tip in rabbits, whereas, in rats, fluctuations in putrescine level were marked. In the six zones of the rabbit kidney studied, spermidine and spermine concentrations were markedly higher in females than in males. This difference was less marked in rats.

Keywords: Keywords: Amino acids – Polyamines – Putrescine – Spermidine – Spermine – Sex differences – Mammalian species

Homocysteine, vitamins B₆, B₁₂, folate, and risk of coronary artery disease in patients undergoing diagnostic coronary angiography by I. Abdelmouttaleb; N. Danchin; I. Aimone-Gastin; F. Namour; M. Angioi; M. -A. Gelot; N. Bennani; D. Lambert; C. Jeandel; J. L. Guéant (pp. 139-146).

Homocysteine and vitamins B were correlated with coronary artery disease in patients undergoing diagnostic coronary angiography. 160 patients having ≧1 stenosis (G1), 55 patients having normal coronary arteries (G2) and 171 healthy volunteers (G3) were prospectively recruited.Homocysteine levels were significantly higher in patients, particulary in those with normal coronary angiograms, than in healthy subjects (13.8 ± 6.3 μmol/L in G1 (p < 0.0001) and 15.2 ± 8.8 μmol/L in G2 (p < 0.0001) versus 10.1 ± 3.1 μmol/L in G3). Homocysteine levels were not related to the extent of coronary artery disease. In patients with normal angiogram, vitamin B12 and folate levels were significantly higher compared with the other groups (p < 0.05 and p < 0.001, respectively) showing that vitamin B deficiency was not involved in the hyperhomocysteinemia.In conclusion, homocysteine and vitamins B levels do not contribute to discriminate for the presence of coronary artery disease in patients undergoing diagnostic coronary angiography. Homocysteine levels, however, were higher in patients referred for coronary angiography than in healthy controls.

Keywords: Keywords: Amino acids – Homocysteine – Vitamin B12 – Vitamin B6 – Folates – Coronary artery disease

Effects of hypoxia on plasma amino acids of fetal sheep by V. Walker; A. J. Gentry; L. R. Green; M. A. Hanson; L. Bennet (pp. 147-156).

Secondary amino acid disturbances from circulatory responses during hypoxia may cause problems in interpreting plasma amino acid profiles of sick babies investigated for possible inherited defects. Systematic studies to characterise them are difficult in man. We investigated the effects of hypoxia on plasma amino acids by studying 9 late gestation fetal sheep in utero during 11 one hour episodes of moderately severe isocapnic hypoxia. In 6 experiments, maternal plasma amino acids were also monitored. Fourteen fetal plasma amino acids increased significantly, with the largest proportionate changes in alanine, valine, leucine, isoleucine, phenylalanine, tyrosine, ornithine and lysine. Maternal amino acids did not increase. Probable explanations were reflex peripheral vasoconstriction in skeletal muscle beds and decreased hepatic blood flow. The findings extend our knowledge of the fetal response to hypoxic stress, demonstrate the importance of skeletal muscle in branched-chain amino acid metabolism, and should help with interpretation of postnatal plasma amino acid disturbances.

Keywords: Keywords: Amino acids – Plasma – Hypoxia – Fetus – Branched-chain amino acids

Importance of proline and other amino acids during honeybee flight by S. Micheu; K. Crailsheim; B. Leonhard (pp. 157-175).

The levels of proline and other amino acids in the haemolymph and other body parts of honeybee foragers were investigated by HPLC analysis. The concentrations of proline in the blood of glucose-fed or -injected bees finishing their exhaustive tethered flights on a roundabout were significantly reduced compared to bees that were fed and rested for one hour. This indicates some utilization of proline during flight metabolism. The levels of essential amino acids and of the sum of all amino acids except proline remained roughly constant, indicating that the decrease of proline did not result from a changed haemolymph volume. ¹⁴C-labelled proline was injected into bees either shortly before starting their flight or before a resting period of equal duration in an incubator at the same temperature. Bees that rested had incorporated more proline into thorax body protein, and less of the labelled substance was unrecovered ("missing") and considered to be respired or less probably defecated. If the entire amount of missing ¹⁴C-proline is regarded as exhaled, the oxidative breakdown of proline reached higher levels after flight than in rested bees. This is another hint that proline is utilized during flight. Usually the exhaled amount did not exceed 10 μg proline in half an hour of flight. Although our data indicate involvement of proline in flight metabolism, the amount metabolized is low compared to the utilization of carbohydrates.

Keywords: Keywords: Amino acids –Apis mellifera– Proline – Foragers – Flight metabolism – Haemolymph

Synthesis and antibacterial activity of some new non-proteinogenic amino acids containing thiazole residues by M. Stanchev; T. Pajpanova; E. Golovinsky (pp. 177-191).

Some new thioamides and thiazoles have been synthesized using canavanine, S-cysteine, homo-S-cysteinesulfonamides and their N-ω-aminoethylated derivatives as adducts in order to investigate the structure-antimicrobial activity relationships. The compounds showed substantial antibacterial activity in vitro against various gram-positive (Staphylococcus aureus, Bacillus cereus etc.) and gram-negative (Escherichia coli, Proteus vulgaris etc.) bacteria. These findings indicate that the presence of the thiazole residue is an essential factor for the antibacterial effect.

Keywords: Keywords: Heterocyclic amino acids – Peptide mimetics – Thiazole – Antimicrobial activity – Canavanine – S-Cysteine- and homo-S-Cysteinesulfonamides – Alkaline protease

Conservation of the basic pattern of cellular amino acid composition during biological evolution in plants by K. Sorimachi; T. Okayasu; K. Akimoto; A. Niwa (pp. 193-197).

The cellular amino acid composition of plant cells was analyzed. The callus of carrot (Daucus carota), leaves of Torenia fournieri and protocomb-like body of Cymbidium, s.p. were examined as examples of plant cells. The cellular amino acid compositions differed in the plant cells, but their basic patterns were quite similar. It is concluded that the basic pattern of the cellular amino acid composition is conserved in all terrestrial organisms, including plants.

Keywords: Keywords: Amino acid – Cellular amino acid – Evolution – Plant cells

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.18, #2)

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Amino Acids: The Forum for Amino Acid, Peptide and Protein Research (v.18, #2)