ISOENZYME DER p–CUMARAT : CoA LIGASE AUS ZELLSUSPENSIONSKULTUREN VON GLYCINE MAX

Abstract

Cell suspension cultures of soybean (Glycine max L.) were grown either in 2–1 Erlenmeyer flasks or in small (12 I) or large (300 l) fermenters. In a crude homogenate of the cells, an enzyme activity was detectable which converted cinnamic acids to the corresponding coenzyme A thiol esters in the presence of ATP, Mg ²⁺ , and Coenzyme A. Upon purification on a DEAE–cellulose column, two p-coumarate : coA ligaše isoenzymes could be separated which also differed by migrating to different positions on polyacrylamide gels. Both enzymes were specific for cinnamic acids as substrates, but they differed greatly with respect to their Km values. In crude extracts, the activities of both isoenzymes could be distinguished, when p-coumaric and 3A–dimethoxycinnamic acids were used as substrates. Thus a time course of changes in both enzyme activities during the growth cycle of a soybean cell culture could be obtained. The activities of both isoenzymes reached a maximum concomitant with a peak in the activities of phenylalanine ammonialyase and cinnamic acid 4–hydroxylase, two further enzymes of the general phenylpropanoid metabolism.