Crystal Structure of Precorrin-8x Methyl Mutase | Academic Article individual record

BACKGROUND: The crystal structure of precorrin-8x methyl mutase (CobH), an enzyme of the aerobic pathway to vitamin B12, provides evidence that the mechanism for methyl migration can plausibly be regarded as an allowed [1,5]-sigmatropic shift of a methyl group from C-11 to C-12 at the C ring of precorrin-8x to afford hydrogenobyrinic acid. RESULTS: The dimeric structure of CobH creates a set of shared active sites that readily discriminate between different tautomers of precorrin-8x and select a discrete tautomer for sigmatropic rearrangement. The active site contains a strictly conserved histidine residue close to the site of methyl migration in ring C of the substrate. CONCLUSION: Analysis of the structure with bound product suggests that the [1,5]-sigmatropic shift proceeds by protonation of the ring C nitrogen, leading to subsequent methyl migration.

author list (cited authors)
Shipman, L. W., Li, D., Roessner, C. A., Scott, A. I., & Sacchettini, J. C.
publication date
Elsevier BV Publisher
published in
Structure Journal
  • Precorrin-8x
  • Vitamin B-12
  • Sigmatropic Rearrangement
citation count