[Catalytic properties of E. coli tryptophanase in a 50% aqueous solution of methanol and dimethylformamide]. / Kataliticheskie svoistva triptofanazy iz E. coli v 50% vodnykh rastvorakh metanola i dimetilformamida.

Tryptophanase from E. coli retains its ability to form quinonoid intermediate with L-alanine in water--methanol and water--dimethylformamide (1:1 v/v) solutions. Under these conditions the enzyme catalyzes decomposition of S-o-nitrophenyl-L-cysteine (SOPC) to o-nitrophenylthiol, pyruvate and ammonium ion. The enzyme's affinity for this substrate increases on going from water to water-organic solvents whereas the reaction rate decreases. In 50% methanol tryptophanase catalyzes the formation of L-tryptophan from indole and SOPC; in the mixture of 2H2O and C2H3O2H (1:1) the enzymatic isotope exchange of alpha-proton of L-phenylalanine with complete retention of configuration was observed.

[The composition of amino acid-peptide mixtures obtained during hydrolysis of proteins]. / Issledovanie sostava aminokislotnykh-peptidnykh smesei, poluchaemykh pri gidrolize belkov.

The composition of the amino acid and peptide fraction of the protein hydrolyzate and its dependence upon the spray-drying process at elevated temperatures were investigated by GLC and GLC-MS. Spray-drying leads to decrease in the Glu and Met contents, to transformation of Cys into cystine and to formation of lactames (pyroglutamic acid and pyrrolidone) and diketopiperazines. Some dipeptides, acetylproline, paraffines, fatty acid pyridinecarboxylic and lactic acids, ethylene glycol were identified in the fraction. The incidental occurrence of these compounds should be taken into account when investigating the biological activity of protein hydrolyzates.

[Amino acid analysis of culture media and autolysates by capillary gas chromatography]. / Aminokislotnyi analiz kul'tural'nykh sred i avtolizatov metodom kapilliarnoi gazovoi khromatografii.

N-heptofluorbutyryl-O-propyl ethers from 20 natural amino acids were analysed on a capillary column Am-Ac by gas chromatography. A high reproducibility of the quantitative estimation of the compounds studied was achieved not only for the standard mixtures but when analysing the amino acid composition of the autolysates of the baker's yeast and cultural media.