Abstract
The specific activities of the nicotinamide adenine dinucleotide phosphate-dependent isocitrate dehydrogenase in crude cell-free extracts of 15 different microorganisms, grown aerobically in simple mineral salts media containing glucose as the sole carbon source, ranged from a maximum of 0.820 in Pseudomonas aeruginosa to a minimum of 0.145 in Thiobacillus novellus. Polyacrylamide gel electrophoresis indicated that the bacterial species studied contained electrophoretically distinct proteins exhibiting isocitrate dehydrogenase activity. The electrophoretic mobilities, as well as the differences in stability of the enzyme observed in this study, indicate that the physical and chemical properties of isocitrate dehydrogenase may differ widely between bacterial species.