Some properties of p-coumarate decarboxylase from Cladosporium phlei

Abstract

The optimal pH and temperature of p-coumarate decarboxylase were 6.0 and 23 °C, respectively. The enzyme activity was reduced to three quarters by heat treatment at 35 °C for 5 min and by half at 25 °C in 24 h, but kept almost unchanged at −20 °C at least for l0 days. The activity was not inhibited by potassium cyanide, sodium diethyldithiocarbamate, ethylenediaminetetraacetic acid disodium salt, or sodium citrate at 10 mM concentration, but was inhibited by p-chloromercuribenzoate or iodoacetate at 0.1 mM, the inhibition by the former being prevented to a great extent by the presence of reduced glutathione or dithiothreitol. The activity was inhibited by maleic acid, cinnamic acid, or p-methoxycinnamic acid, but not by fumaric acid, acrylic acid, p-hydroxystyrene, furcatin, p-hydroxyphenylacetic acid, or phloretic acid. An unsubstituted p-hydroxy group on the benzene ring and an acrylic acid side chain were required for the enzyme activity. Km value for trans- p-coumaric acid was about 6.5 × 10−4 M.