Manganese(II) activation of 3-phosphoglycerate mutase of Bacillus megaterium: pH-sensitive interconversion of active and inactive forms.
The effects of manganese(II) ions and of pH were studied on 3-p-glycerate mutase purified from Bacillus megaterium. Mn2+ ions converted the enzyme within a few minutes from a catalytically inactive form to one that was catalytically active even after Mn2+ had been removed. The enzyme reverted over 60-90 min to the inactive form, from which further activation-deactivation cycles could be elicited. The slow, temperature-dependent, activation, and deactivation is suggestive of change in protein conformation. No other metal ion was found that activated more than 4% as much as Mn2+. Activation by Mn2+ was strongly pH-dependent in the physiological pH range, consistent with displacement of 2 H+. Together with the pH dependence of the catalytic activity itself, the system displayed pronounced pH sensitivity in the pH range 6.5-8.0. The findings suggest that pH changes, documented for forming and germinating spores of B. megaterium, can account for much of the mutase control associated with accumulation and later utilization of 3-phosphoglycerate depots.
Kuhn
N J
NJ
School of Biochemistry, University of Birmingham, United Kingdom.
Setlow
B
B
Setlow
P
P
D001410:Bacillus megaterium / Q000201:enzymology*; D002413:Cations, Divalent / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology*; D010736:Phosphoglycerate Mutase / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology
D002413:Cations, Divalent; D008345:Manganese; D004492:Edetic Acid; D010736:Phosphoglycerate Mutase; D011188:Potassium