MARINE PSYCHROPHILE A CELL-FREE EXTRACT FROM DEHYDROGENASE IN A RENATURATION OF MALIC DENATURATION AND

ABSTRACT BURTON, SHERIL D. (Oregon State University, Corvallis), AND RICHARD Y. MORITA. Denatura-tionandrenaturationofmalicdehydrogenaseina cell-free extract from a marine psychrophile. J. Bacteriol. 86:1019-1024. 1963.-Malic dehy- drogenase from a marine psychrophilic vibrio (PS207) was found to beheat-sensitive at 30 C, the maximal growth temperature for the or- ganism. Initial denaturation was reversible, withmaximal renaturation occurring when the de-naturedenzymewasslowlycooledinthepresenceof mercaptoethanol, reduced nicotinamide ade- nine dinucleotide, and malate. No renaturation occurred when these compounds were added after slow cooling, or when the renaturationmixturewasrapidly cooled. Mercaptoethylamine, cysteine, glutathione, or mercaptoacetic acid could not replace mercaptoethanol. The kineticsof denaturation and renaturation suggest thepresence of several malic isozymes each with different heat labilities, or that these processesare occurring in several distinct steps. Theinability ofamarineisolate to grow