Isolation and Partial Characterization of Alcohol Dehydrogenase From Broad Bean (Vicia faba)

Abstract

Alcohol dehydrogenase isolated from broad bean was found to have a K_m value of 1.0 × 1.0 ^-2 M, a pH optimum of 8.7 and a molecular weight of 60 000 ± 5000. The enzyme lost 55 % of its activity after being heated at 55ºC, and was totally inactivated at 70°C. Thermal stability of the enzyme was not enhanced by NAD⁺ or ethanol.

The substrate specificity of the enzyme is reported. Cysteine and mercaptoethanol activated the enzyme, whilep-chloromercuribenzoate, Cu²⁺, Hg²⁺, B₄O₇^2- -, Zn²⁺ and EDTA inhibited it. The influence of ethanol, acetaldehyde and growth substances on alcohol dehydrogenase activity in germinating broad bean seeds and plant tissues was also studied.