10016. Cob(II)alamin

Nomenclature

CAS number: 14463-33-3
Vitamin B12-Co(II); 5,6-dimethyl-1-(3-O-phosphono-α-d-ribofuranosyl)-1H-benzimidazole monoester with cobinamide-Co(II) inner salt; vitamin B12r; reduced vitamin B12.
C62H88CoN13O14P; mol wt 1329.35.
C 56.02%, H 6.67%, Co 4.43%, N 13.70%, O 16.85%, P 2.33%.

Description and references

A one-electron reduction product of vitamin B12 containing a 5-coordinate 2+ cobalt atom. Undergoes a further one-electron reduction to cob(I)alamin. Intermediate in biosynthesis of cobamamide and in cobalamin-dependent reactions. Prepn: H. Diehl, R. Murie, Iowa State Coll. J. Sci. 26, 555 (1952); R. O. Brady, H. A. Barker, Biochem. Biophys. Res. Commun. 4, 373 (1961) DOI; H.-U. Blaser, J. Halpern, J. Am. Chem. Soc. 102, 1684 (1980) DOI. Valence of reduced forms of B12: H. A. O. Hill et al., Chem. Ind. (London) 1964, 197. Crystal structure: B. Krutler et al., J. Am. Chem. Soc. 111, 8936 (1989) DOI; of biosynthetic intermediates: M. St. Maurice et al., Biochemistry 47, 5755 (2008) DOI PubMed. Review of prepns: D. Dolphin, Methods Enzymol. 18, (Pt. C), 34-52 (1971) DOI; of role in enzymatic reactions: J. M. Pratt, Pure Appl. Chem. 65, 1513 (1993) DOI; G. H. Reed, S. O. Mansoorabadi, Curr. Opin. Struct. Biol. 13, 716-721 (2003) DOI PubMed; M. Yamanishi et al., Trends Biochem. Sci. 30, 304-308 (2005) DOI PubMed.

Chemical structure

Properties

Dark brown amorphous solid. Oxidized by air to aquocobalamin. Absorption max (H2O): 474, 404, 312, 289, 260 nm (log ε 3.99, 3.88, 4.46, 4.29, 4.25).

Derivative

Cob(I)alamin.

Nomenclature

CAS number: 18534-66-2
Cobinamide-Co(I) dihydrogen phosphate (ester) 3′-ester with 5,6-dimethyl-1-α-d-ribofuranosyl-1H-benzimidazole; hydridocobalamin; vitamin B12s.
C62H89CoN13O14P; mol wt 1330.36.
C 55.97%, H 6.74%, Co 4.43%, N 13.69%, O 16.84%, P 2.33%.

Properties

Obtained as a gray-green product in solution.