Fluorinated vitamin b(12) analogs are cofactors of corrinoid-dependent enzymes: a f-labeled nuclear magnetic resonance probe for identifying corrinoid-protein interactions.

The homoacetogenic bacterium Sporomusa ovata synthesized the vitamin B(12) analog phenolyl cobamide or 4-fluorophenolyl cobamide when the methanol medium of growing cells was supplemented with 10 mM phenol or 5 mM 4-fluorophenol. Phenol and, presumably, 4-fluorophenol were specifically incorporated into these cobamides, since phenol was not metabolized significantly into amino acids or into acetic acid, the product of the catabolism. The phenol-containing cobamides contributed up to 90% of the protein-bound cobamides of the 1,300 to 1,900 nmol of corrinoid per g of dry cell material formed.

Evidence for a super-reduced cobamide as the major corrinoid fraction in vivo and a histidine residue as a cobalt ligand of the p-cresolyl cobamide in the acetogenic bacterium Sporomusa ovata.

The redox state of cobalt in p-cresolyl cobamide and one of its axial ligands were determined by EPR spectroscopy of Sporomusa ovata as harvested. The analyses revealed that less than 2% (less than 30 nmol/g dry cells) of the total corrinoids (greater than 2400 nmol/g dry cells) were in a low-spin Co(II) complex. The amount increased to about 15% (190-450 nmol/g dry cells) upon partial oxidation by air, indicating that the original valence state of cobalt was a Co(I) prior to this treatment.

Identification of phenolyl cobamide from the homoacetogenic bacterium Sporomusa ovata.

Phenolyl cobamide was isolated from cyanide extractions of the anaerobic eubacterium Sporomusa ovata. The proposed corrinoid structure [Co alpha,Co beta-(monocyano,monoaquo)-phenolyl cobamide] has been deduced from 1H NMR, fast-atom-bombardment mass spectroscopy and ultraviolet/visible spectroscopy data. The complete corrinoid resembled p-cresolyl cobamide [Co alpha,Co beta-(monocyano,monoaquo)-p-cresolyl cobamide], which recently has been obtained from cyanide extractions of the same bacterium.

Diversity of corrinoids in acetogenic bacteria. P-cresolylcobamide from Sporomusa ovata, 5-methoxy-6-methylbenzimidazolylcobamide from Clostridium formicoaceticum and vitamin B12 from Acetobacterium woodii.

The Co beta-cyanocobamides obtained by cyanide extractions from several acetogenic bacteria were structurally characterized by ultraviolet/visible spectra, proton-nuclear-magnetic-resonance spectra and fast-atom-bombardment mass spectra. p-Cresolycobamide was detected as a major corrinoid from Sporomusa ovata. This 'complete' corrinoid was isolated from an organism for the first time.

Substitution of Co alpha-(5-hydroxybenzimidazolyl)cobamide (factor III) by vitamin B12 in Methanobacterium thermoautotrophicum.

Methanobacterium thermoautotrophicum grown on mineral medium contains 120 nmol of Co alpha-(5-hydroxybenzimidazolyl)cobamides (derivatives of factor III) per g of dry cell mass as the sole cobamide. The bacterium assimilated several corrinoids and benzimidazole bases during autotrophic growth. The corrinoids were converted into factor III; however, after three transfers in 5,6-dimethylbenzimidazole (200 microM)-supplemented mineral medium, derivatives of factor III were completely replaced by derivatives of vitamin B12, which is atypical for methanogens.