Studies on the acetone-butanol fermentation

Abstract

An enzyme which decarboxylates acetoacetic acid to acetone has been extracted from acetone-treated cells of Clostridium acetobutylicum, purified and its properties described. The purified enzyme is quite stable at ordinary temps.; it is optimally active at pH 5 and is specific for acetoacetic acid. It is powerfully inhibited by acetopyruvic acid. In dilute soln. the enzyme is dissociated but it has not been possible to separate the component parts. The dissociation can be prevented by a prepn. of diaphorase at a conc. equivalent to 0.07 [gamma] riboflavin/ml. Riboflavin is inactive, as also are co-carboxylase, thiamin monophosphate, adenylic acid, and cozymase. Mild acid hydrolysis (N/20 HCl for 60 min. at 96[degree]) of the diaphorase does not affect its ac- tivity. Riboflavin phosphate may be the prosthetic group of the enzyme.