Adenosylcobalamin-dependent isomerases: new insights into structure and mechanism.
Adenosylcobalamin-dependent isomerases catalyze a variety of chemically difficult 1,2-rearrangements that proceed through a mechanism involving free radical intermediates. These radicals are initially generated by homolysis of the cobalt-carbon bond of the coenzyme. Recently, the crystal structures of several of these enzymes have been solved, revealing two modes of coenzyme binding and highlighting the role of the protein in controlling the rearrangement of reactive substrate radical intermediates. Complementary data from kinetic, spectroscopic and theoretical studies have produced insights into the mechanism by which substrate radicals are generated at the active site, and the pathways by which they rearrange.
Marsh
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Department of Chemistry and Division of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA. nmarsh@umich.edu
Drennan
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D001665:Binding Sites; D002384:Catalysis; D003038:Cobamides / Q000737:chemistry*; D004735:Energy Transfer; D006868:Hydrolysis; D007535:Isomerases / Q000737:chemistry*; D015394:Molecular Structure; D011487:Protein Conformation
D003038:Cobamides; D007535:Isomerases; C000913:cobamamide