||This bacterial enzyme utilizes 5′-deoxyadenosylcobalamin as a cofactor. Following substrate binding, the enzyme catalyses the homolytic cleavage of the cobalt-carbon bond of AdoCbl, yielding cob(II)alamin and a 5′-deoxyadenosyl radical, which initiates the the carbon skeleton rearrangement reaction by hydrogen atom abstraction from the substrate. At the end of each catalytic cycle the 5′-deoxyadenosyl radical and cob(II)alamin recombine, regenerating the resting form of the cofactor. The enzyme is prone to inactivation resulting from occassional loss of the 5′-deoxyadenosyl molecule. Inactivated enzymes are repaired by the action of EC 188.8.131.52, cob(I)yrinic acid a,c-diamide adenosyltransferase, and a G-protein chaperone, which restore cob(II)alamin (which is first reduced to cob(I)alamin by an unidentified reductase) to 5′-deoxyadenosylcobalamin and load it back on the mutase. Some mutases are fused with their G-protein chaperone. These enzyme can also catalyse the interconversion of isovaleryl-CoA with pivalyl-CoA.
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||Ratnatilleke, A., Vrijbloed, J.W. and Robinson, J.A. Cloning and sequencing of the coenzyme B12-binding domain of isobutyryl-CoA mutase from Streptomyces cinnamonensis, reconstitution of mutase activity, and characterization of the recombinant enzyme produced in Escherichia coli. J. Biol. Chem. 274 (1999) 31679–31685. [DOI] [PMID: 10531377]
||Cracan, V., Padovani, D. and Banerjee, R. IcmF is a fusion between the radical B12 enzyme isobutyryl-CoA mutase and its G-protein chaperone. J. Biol. Chem. 285 (2010) 655–666. [DOI] [PMID: 19864421]
||Cracan, V. and Banerjee, R. Novel coenzyme B12-dependent interconversion of isovaleryl-CoA and pivalyl-CoA. J. Biol. Chem. 287 (2012) 3723–3732. [DOI] [PMID: 22167181]
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||Li, Z., Kitanishi, K., Twahir, U.T., Cracan, V., Chapman, D., Warncke, K. and Banerjee, R. Cofactor editing by the G-protein metallochaperone domain regulates the radical B12 enzyme IcmF. J. Biol. Chem. 292 (2017) 3977–3987. [DOI] [PMID: 28130442]