PARTIAL DENATURATION OF A BACTERIAL ALDOLASE WITHOUT LOSS OF ACTIVITY

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Abstract
Treatment of aldolase isolated from Bacillus stearothermophilus with sulfhydryl compounds decreases its stability toward heat, but concurrently increases activity. Stimulation with these compounds is instantaneous, whereas at least 2 hours incubation prior to assay are required for maximum loss of heat stability. There is a marked difference between the sulfhydryl-treated and untreated enzyme. After 1 hour at 65[degree]C, the untreated enzyme showed no loss of activity whereas the activity of the sulfhydryl-treated enzyme declined to 30% of its optimal activity. Kinetic studies suggest that sulfhydryl treatment results in a mild alteration of the enzyme. Differences in activation energies and heats of reactions are slight. However, differences in Michaelis constants becomes almost 10-fold at 30[degree]C, but less at more elevated temperatures.