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

Publisher Website
Google Scholar
Abstract
Malic dehydrogenase from a marine psychrophilic Vibrio (PS 207) was found to be heat-sensitive at 30 C, the maximal growth temperature for the organism. Initial denaturation was reversible, with maximal renaturation occurring when the denatured enzyme was slowly cooled in the presence of mercaptoethanol, reduced nicotinamide ade-nine dinucleotide, and malate. No renaturation occurred when these compounds were added after slow cooling, or when the renaturation mixture was rapidly cooled. Mercaptoethylamine, cysteine, gluta-thione, or mercaptoacetic acid could not replace mercaptoethanol. The kinetics of denaturation and renaturation suggest the presence of several malic isozymes each with different heat labilities, or that these processes are occurring in several distinct steps.