[Nature of wine yeast glutamate dehydrogenase inhibition by adenylic nucleoside phosphates]. / O kharaktere ingibirovaniia glutamatdegidrogenazy vinnykh drozhzhei adenilovymi nukelozidfosfatami.

The mode of inhibition of NADP-dependent glutamate dehydrogenase by adenylic nucleoside phosphates (ATP, ADP, AMP) was studied with Saccharomyces vini. AMP was found to be a competitive inhibitor for glutamate dehydrogenase whereas the action of ADP and ATP was of a mixed character.

[Examination of the action of effectors after storing glutamine synthetase from the fodder yeast Candida tropicalis at room temperature]. / Issledovanie kharaktera deistviia effektorov posle vyderzhivaniia gliutaminsintetazy kormovykh drozhzhei pri komnatnoi temperature.

The pattern of action of effectors (AMP, IMP, CMP, anthranilic acid, tryptophane, alanine, glutamine, glycine, histidine) and glutamine synthetase (GS) extracted from the fodder yeast Candida tropicalis and stored at room temperature for 1.5-2 hrs was examined. As regards the action of effectors on GS after its exposure at room temperature, they can be subdivided into four groups: 1) the effector loses completely its inhibitory effect (glutamine, CMP, anthranilic acid in the synthetase reaction); 2) the inhibitory effect on the enzyme increases (AMP, IMP, anthranilic acid in the transferase reaction); 3) at low concentrations of the effector the peak of activation appears (tryptophane, GMP, alanine, glycine); 4) at low concentrations of the enzyme two peaks of activation appear (histidine). Similar results were obtained with the purified preparation of GS.

[Thermostability of glutamine synthetase in Candida tropicalis feed yeasts in Mg-, Mn- and Co-activated systems]. / Termostabil'nost' glutaminsintetazy u kormovykh drozhzhei Candida tropicalis v Mg-, Mn- i Co-aktiviruemoi sistemakh.

The thermostability of glutamine synthetase of Candida tropicalis was studied in systems activated by Mg, Mn and Co. The enzyme was found to be very thermolabile. Its thermostability depended on the nature of a bivalent cation used in the reaction mixture. Metals stabilized the enzyme since preincubation with metal cations increased the thermostability of glutamine synthetase. Purification of the enzyme preparation increased the stabilizing action of bivalent cations (Mg2+, Mn2+, Co2+).

[Purification and properties of the NADP-specific glutamate dehydrogenase of Candida tropicalis feed yeasts]. / Ochistka i nekotorye svoistva NADF-spetsifichnoi glutamatdegidrogenazy kormovykh drozhzhei Candida tropicalis.

From the cell-free extract of fodder yeast Candida tropicalis NADP-specific glutamate dehydrogenase was isolated and partially purified (75-fold) by means of fractional precipitation by ammonium sulphate and ion-exchange chromatography on DEAE-cellulose. The preparation was investigated with the aid of polyacrylamide gel electrophoresis. Kinetic characteristics of the enzyme in the cell-free extract and partially purified preparation were derived.

[Effect of p-chloromercuribenzoate on glutamine synthetase in the food yeast Candida tropicalis]. / Vliianie p-khlormerkuribenzoata na glutaminsintetazu kormovykh drozhzhei Candida tropicalis.

The effect of p-CMB on the activity of glutamine synthetase in the fodder yeast Candida tropicalis was studied in the synthetase reaction in Mg-, Mn-, and Co-activated systems and in the transferase reaction. The activity of glutamine synthetase was inhibited by pCMB, the degree of inhibition depending on the presence of bivalent cations of metals. Preliminay incubation of the enzyme with p-CMB stimulated the action of the latter, whereas metals increased the stability of the enzyme to pCMB. If the enzyme preparation was purified, it became more susceptible to the action of p-CMB. The transferase activity was also inhibited by p-CMB but to a less extent that the synthetase reaction.

[Regulation of fodder yeast Candida tropicalis glutamine synthetase activity by the end products of glutamine metabolism]. / Reguliatsiia aktivnosti glutaminsintetazy kormovykh drozhzhei Candida tropicalis konechnymi produktami obmena glutamina

Effect of different products of glutamine metabolism on the activity of glutamine synthetase in the presence of Mg2+, and Mn2+ and Co2+ as cofactors is studied. All the metabolites studied are found to inhibit the glutamine synthetase activity in the presence of any cation listed. The degree and the character of the inhibition by one or other metabolite depended in a considerable degree on the nature of the cation presented in the reaction mixture (Mg2+, Mn2+ or Co2+). The mechanism of the cumulative effect of retroinhibitors under the change of Mg2+ or Mn2+ in the reaction mixture was the same.