[Mutagenic activity of industrial chemical reagents in various tests]. / Izuchenie mutagennoi aktivnosti promyshlennykh khimreagentov v raznykh testakh.

Testing of 37 industrial chemical reagents has revealed ten substances with a mutagenic effect. The necessity of using several tests to detect the type and level of mutagenic lesions is emphasized.

[Substrate and inhibitory specificity of riboflavin kinase from Pichia guilliermondii yeast]. / Issledovanie substratnoi i ingibitornoi spetsifichnosti riboflavinkinazy iz drozhzhei Pichia guilliermondii.

The interaction of purified riboflavin kinase (EC 2.7.1.26) from Pichia guilliermondii with 44 structural vitamin B2 analogues is studied. The presence of D-ribityl lateral chain in an analogue structure is found to be necessary for the substrate activity. The substitution of CH3 groups in the 7 and 8 positions of isoalloxazine ring in the riboflavin molecule for CF3, Cl, H, NH2 and N(CH3)2 resulted in the decrease of the analogue affinity to riboflavin kinase as compared with the natural substrate, vitamin B2. The most efficient enzyme inhibitors of analogues without substrate properties turned to be trifluoromethylisoalloxazines, containing 2'-hydroxyethyl group at N10. The elongation of D-ribityl lateral chain, the elimination of change of CH3-groups in the 7 and 8 positions for CF3- Cl-, COOH-substitutors resulted in the decrease of the inhibitory effect of flavines. Modifications in the structure of isoalloxazine ring, etherification of OH-groups in the lateral D-ribityl chain, and the introduction of volume substitutors (N-piperidyl, D-ribitylamine, hydroxyethylamine) prevented the interaction of the analogue with riboflavin kinase. Flavin nucleotides (FMN and FAD) did not affect the rate of vitamin B2 phosphorylation.