2-METHYL-L-TRYPTOPHAN IS A SUBSTRATE OF TRYPTOPHANASE

Tryptophanase was generally considered to be inactive towards tryptoph an derivatives substituted at 2-position of the indole ring. We have s hown that cells containing tryptophanase catalyze the formation of 2-m ethyl-L-tryptophan from 2-methylindole and L-serine, and from 2-methyl indole, pyruvate and ammonium ion. The kinetics of pyruvate formation from 2-methyl-L-tryptophan and its alpha-deuterated analogue catalyzed by homogeneous tryptophanase were examined. The primary deuterium iso tope effect(k(H)/k(D) = 4.0) as well as the absorption spectrum of try ptophanase complex with 2-methyl-L-tryptophan indicate that the rate o f enzymatic reaction of 2-methyl-L-tryptophan is in considerable degre e determined by the stage of removal of alpha-proton.