Translation Series No. 906

1. The existence of malic enzyme (EC 1.1.1.40 1-malate: NADP oxidoreductase), has been discovered in the muscle extract from mollusca. A procedure for the preparation of purified enzyme is presented. 2. After extracting with potassium chloride solution, purification was carried out with fractional precipitation by ammonium sulphate, adsorption with calcium phosphate gel and fractionation by DEAE-cellulose column. 3. In squid mode (ammastrephes sloani paci ficus), the final product had a ten-times higher specific activity. Optimum pH is 7.1-7.2. It is stable between pH 6.5 and 7.5 at 30°C, but unstable at temperatures above 35°C. The enzyme is activated by Mg" and Mn" ions. Michaelis constant is 1.33><10'M for malate and 0.66 x10-2 M for NADP. 4. In Scallop (Pecten yessoensis), the enzyme has been purified three-fold. The behaviour of it on a DEAE-cellulose column was shown to differ from that of squid. Other properties were thé same as that of squid, except there was less stability. 5. The significance of the malic enzyme in mollusca was discussed.