The vitamin B12 group. Presence of 2-methyl purines in factors A and H and isolation of new factors

Abstract

' vitamin B12 ' titres obtained by Dulaney & Williams (1953). 6. The biosynthesis of true vitamin B12 is competitively inhibited by phenylenediamine. 7. The biosynthesis of the new material in the presence of phenylenediamine is competitively inhibited by 1:2-diamino-4:5-dimethylbenzene. The inhibition index lies somewhere between l60 and 320. The authors wish to express their thanks to Miss R. A. Brill and to Miss C. M. Lovejoy for valuable technical assistance. Note added in proof. Clinical trials kindly carried out by Professor L. J. Witts and Dr Sheila Callendar at the Radcliffe Infirmary, Oxford, showed that the new material was fully active in three pernicious anaemia patients.

A bioassay for the detection of benzimidazoles reveals their presence in a range of environmental samples

“…The gastrointestinal tracts of several animals have been found to contain high concentrations of corrinoids. Bovine rumen, ovine tissue, wood-feeding insects, and the feces of humans, cows, and pigs have concentrations of corrinoids up to 2 μg per gram of sample, though the concentrations of free benzimidazoles in these environments have not been reported ( Brown et al, 1955 ; Wakayama et al, 1984 ; Kelly et al, 2006 ; Allen and Stabler, 2008 ; Girard et al, 2009 ). We detected approximately 300 pM DMB equivalents in each of two bovine rumen fluid samples, while in termite fecal pellets ∼0.9 pmol/g was detected ( Table 2 ).…”

COBALAMIN (COENZYME B12): Synthesis and Biological Significance

“…Cobalamin is prepared commercially with a cyano group as the Coβ ligand; this form (CN-B 12 ) is not found in nature but frequently is used as a nutrient for humans and for bacterial mutants. Alternative forms of B 12 with different bases in place of Dmb have been identified in various Bacteria and Archaea (35,63,72,156,157). These corrinoids appear to be isofunctional; no correlation has been made between the nucleotide used as the lower ligand and the function or distribution of a corrinoid (156).…”

Identification and quantitation of cobalamin and cobalamin analogues in human feces

“…Feces contain a large number of microorganisms (9,10) and previous studies have indicated that Cbl and a number of Cbl analogues are present in significant amounts (11)(12)(13). Early studies of Cbl analogues used paper chromatography and electrophoresis and the fact that Cbl and a number of naturally occurring Cbl analogues differ in their ability to stimulate the growth of certain microorganisms (11,12). These studies showed that Cbl analogues were major components of feces from numerous animals.…”