3-Hydroxyl-3-methylglutaryl coenzyme A synthase activity in Hevea braziliensis and its possible role in regulation of rubber synthesis

Oluoha Ukazu


The activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase from rubber (Hevea
brazilliensis) latex and from fractions obtained by centrifugation was determined using spectrophotometric method.
The enzyme was present in all the fractions except rubber but was most abundant in C-serum. The enzyme obeys
Michaelis-Menten kinetics and has a Km value of 10 mM for acetyl CoA. The enzyme is inhibited by several divalent
cations, p-chloromercuribenzoate and dithiothreitol but activated by EDTA. Cd2+ is the most potent inhibitor among
all the cations examined. Diurnal variation in enzyme activity was observed. The positive correlation between enzyme
activity and rubber content of the latex suggests that the enzyme regulates the biosynthesis of rubber in the latex.
Key Words: HMG-CoA; HMG-Co A synthase; Rubber (Hevea brazilliensis); Rubber synthesis; Enzyme kinetics.

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