NADPD ISOTOPE EFFECT ON ACTIVITY OF EMODIN DEOXYGENASE

Article abstract of DOI:10.1016/0031-9422(93)85210-I

Thermoanaerobium brokii alcohol dehydrogenase catalysed the transfer of the pro 4H, hydrogen of NADPH.The effect of 4-deuteration of NADPH on the initial rate of conversion of emodin to chrysophanol catalysed by emodin deoxygenase was determined.The deuterium isotope effects on V/K_m and V_max with <4R-2H>NADPH were 1.20 +/- 0.36 and 1.10 +/- 0.11, respectively.The deuterium isotope effects on V/K_m and V_max with <4S-2H>NADPH were 4.08 +/- 1.55 and 6.90 +/- 0.74, respectively.Emodin deoxygenase, therefore, transfers the 4S hydrogen of NADPD in the rate-determining step.Key word index - Pyrenochaeta terrestris; Sphaeropsidaceae; emodin; chrysophanol; deoxygenase; <4H²>NADPH; kinetics.