3-Hydroxy-2methylglutaryl coenzyme A reductase (Mevalonate : NADP + oxidoreductase acylation Coa

EC 1.1.1.34) was purified from fresh Hevea rubber latex of clone RRIM 600. The latex was fractionated by centrifugation at 49,000 g for 60 min. Bottom fraction were pooled and used for enzyme purification. The enzyme was solubilized from the bottom fraction (lutoid) by freeze-thawing in the solubilization buffer containing 1% Brij W-1 and 20% glycerol. Further purification of the solubilized enzyme was achieved by (NH(,4))(,2)SO(,4) precipitation followed by column chromatography on DEAE-Sephadex A-50, Affi-Gel Blue and HMG-CoA-hexane-agarose respectively. The final affinity chromatography step led to 257.7 fold of purification with a specific activity of 105.6 nmoles MVA formed/min/mg of purified enzyme. The relative molecular mass determined by SDS-PAGE was 44,000 and that estimated from non-denaturing gel electrophoresis 176,000. The optimal pH fo rits activity was found to be around 7.0, with an apparent Km of 13 uM for (S) - HMG-CoA. The concentration of dithiothreitol required for maximal activity of the enzyme was mM. The enzyme fraction obtained from column chromatography on AffiGel Blue was used to raise antibody in Ne Zealand White rabbit. Maximum enzymic inhibition due to the presence of varying concentration of rabbit antiserum was 29.8%.