Isopentenyl diphosphate isomerase in rubber latex

Abstract

Isopentenyl diphosphate isomerase (EC 5.3.3.2), which catalyses the reversible isomerization of isopentenyl diphosphate to dimethylallyl diphosphate, is presumed to be involved in rubber biosynthesis, but no direct evidence has been given for its occurrence in rubber latex. This enzyme activity was found in the C-serum powder prepared by lyophilization of centrifuged rubber latex of Hevea brasiliensis. Characterization of partially purified enzyme showed a K(m) value of 71 μM for isopentenyl diphosphate, a pH optimum of 7 and an optimum temperature at 37°. Divalent cations (Mg2+or Mn2+) and dithiothreitol are required for maximum enzymic activity. Sulphhydryl reagents such as iodoacelamide, p-chloromercuribenzoale and N- ethylmaleimide are effective inhibitors.