Monovalent Cation Activation of IMP Dehydrogenase

摘要

IMP dehydrogenases are among the group of enzymes that require specific monovalent cations for maximal catalytic activity. These cations function in catalysis rather than in maintenance of global protein structure. In the IMP dehydrogenase catalyzed reaction, the ions specifically facilitate hydride transfer from the covalent enzyme-IMP intermediate to NAD, rather than either formation of enzyme-IMP or hydrolysis of the oxidized enzyme-XMP* intermediate. Possible mechanisms by which monovalent cations may fulfill this role are discussed.