787. Chemistry of the vitamin B12 group. Part III. The course of hydrolytic degradations

Abstract

The hydrolysis of vitamin BIZ under a wide variety of experimental conditions has been studied. Electrophoresis on paper has proved most useful for analysing the complex mixtures of basic, neutral, and acidic products so formed. Vitamin BIZ contains three primary amide groups, which can be hydrolysed stepwise, under comparatively mild conditions, to the corresponding acids. The acids so obtained, three mono-, three di-, and one tri-basic, have all been reconverted into the parent vitamin. Conditions for the hydrolytic removal of the 5 : 6-dimethylbenziminazole nucleotide, both before and after hydrolysis of the amide groups, have been defined and the crystalline free nucleotide has been isolated. 1-Aminopropan-2-01 is believed to be attached by ester linkage to the nucleotide and by amide linkage to the rest of the molecule. The moderately stable cobalt-containing end products from vigorous acid hydrolysis contain five, six, and seven acidic groupings and, from alkaline hydrolysis, five and six acidic groupings.THE combined results of the degradative work so f a r reported on vitamin B,, the antipernicious anaemia factor, have led to the partial formula ( I ) for the vitamin. Its precise molecular formula is not known with certainty, but C,,_,H84-92013-14NlpPCo covers the * A feature of the structure ( I ) is the 5 : 6-dimethyl-l-(a-D-ribofuranosyl)benzhinazoIe-2'(or 3') phosphate residue, which must be fully esterified as the vitamin itself contains no free acidic groups. The benziminazole nucleotide has been isolated from the products of acid hydrolysis of vitamin B,,, both as the barium salt (Buchanan, Johnson, Mills, and Todd, J., 1950, 2845) and as the free acid (Kaczka, Heyl, Jones, and Folkers, J . Amer. Chem. SOC., 1952, 74, 5549; see also Experimental section), and a synthesis has been reported (Kaczka et al., Zoc. cit.), although the point of attachment of the phosphate to the sugar side-chain (i.e,, whether 2' or 3') is still uncertain. The corresponding nucleoside has also been isolated from acid hydrolysates (Brink and Folkers, J . Amer. Chem. SOC., 1952, 74, 2856) and its structure, 5 : 6-dimethyl-l-(~~-~-~bofuranosyl)benz~~nazole, has been confirmed by synthesis (Holly, Shunk, Peel, Cahill, Lavigne, and Folkers, ibid., p. 4521) ; 5 : 6-dimethylbenzirninazole itself has been isolated from the products of vigorous acid hydrolysis of the vitamin (Brink and Folkers, ibid., 1950, 72, 4442; Beaven, Holiday, Johnson, Ellis, Mamalis, Petrow, and Sturgeon, J . Pharm. Pharmacol., 1949, 1, 957).Ammonia and D,-1-aminopropan-2-01 (Wolf, Jones, Valiant, and Folkers, J . Amer. Chem. SOC., 1950, 72, 2820) are also produced on acid hydrolysis, and it has been claimed by Chargaff, Levine, Green, and Kream (Exferientia, 1950, 6, 229) that two moles of the alkanolamine and four-five moles of ammonia are formed from each mole of the vitamin after hydrolysis with G~-hydrochloric acid for 6 hr. at 100" in a sealed tube. On the other hand Cooley, Davies, Ellis, Petrow, and Sturgeon ( J . Pharm. Pharmacol., 1953, 5, ...

Reduction of Heliotrine by A Rumen Microorganism

“…The band with RF twice that of vitamin Bn was eluted in ethanol and dried. The spectrum of this material agreed with that reported by Armitage et al (1953) for factor B.…”

Inhibition of cobalamin-dependent enzymes by cobalamin analogues in rats.

“…Analogues with substitutions at the e-propionamide side chain of the C-ring were made by a modification of the methods of Armitage (27) (25).…”

Absorption, Plasma Transport, and Cellular Retention of Cobalamin Analogues in the Rabbit

“…The fact that some naturally occurring analogues are inactive (17) (23) in which CN-Cbl was incubated at 65°C for 6 min in concentrated HC1. The sample was diluted with 10 vol of H20, and the chloride was removed by application to a 2.0 x 30-cm column of Dowex AG 1 x 8 acetate, equilibrated in H20 at 4°C.…”