Catalytic properties of tryptophanase from E. coli in 50% aqueous solutions of methanol and dimethylformamide

N. G. Faleev, M. B. Saporovskaya, V. M. Belikov, I. S. Sakharova, L. N. Zakomirdina, Yu. M. Torchinsky

A. N. Nesmeyanov Institute of Organo-Element Compounds, Academy of Sciences of the USSR, Moscow; V. A. Engelhardt Institute of Molecular Biology, Academy of Sciences of the USSR, Moscow

Abstract: 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 α-proton of L-phenylalanine with complete retention of configuration was observed.

Russian Journal of Bioorganic Chemistry 1990, 16 (8):1019-1023

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