Coordinated changes in enzyme activities of phenylpropanoid metabolism during the growth of soybean cell suspension cultures

Abstract

Variations in teh activities of several enzymes of phenylpropanoid metabolism were studied in fermenter-grown cell suspension cultures of soyben ( Glycine max). Concomitant large increases and subsequent decreases in the activities of phenylalanine ammonina-lyase (EC 4.3.1.5), cinnamic acid 4-hydroxylase, and two isoenzymes of p-coumarate:CoA ligase occurred prior to the stationary phase of the cell cultures. These findings represent a further example of an interdependent regulation of these enzymes of the general phenylpropanoid metabolism. The increases in all of these enzyme activities could be further enhanced by illunination of the cells. No comparable light effects and no significant changes were observed for the specific activity of an S-adenosylmethionine: o-dihydric phenol m- O-mehyltransferase and for the overall rate of the two-step reduction of feruloyl-CoA to coniferyl alcohol. These enzymatic reactions therefore appear to be regulated independently of the enzymes of the general phenylpropanoid metabolism.