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Curr Opin Chem Biol. 2006 Oct;10(5):520-5. Epub 2006 Aug 17.

IMP dehydrogenase: structural schizophrenia and an unusual base.

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Department of Biochemistry, Brandeis University, Waltham, MA 02454, USA.


Textbooks describe enzymes as relatively rigid templates for the transition state of a chemical reaction, and indeed an enzyme such as chymotrypsin, which catalyzes a relatively simple hydrolysis reaction, is reasonably well described by this model. Inosine monophosphate dehydrogenase (IMPDH) undergoes a remarkable array of conformational transitions in the course of a complicated catalytic cycle, offering a dramatic counterexample to this view. IMPDH displays several other unusual mechanistic features, including an Arg residue that may act as a general base catalyst and a dynamic monovalent cation site. Further, IMPDH appears to be involved in 'moon-lighting' functions that may require additional conformational states. How the balance between conformational states is maintained and how the various conformational states interconvert is only beginning to be understood.

[Indexed for MEDLINE]

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