期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：1995
卷号：41
期号：5
页码：515-526
DOI：10.3177/jnsv.41.515
出版社：Center for Academic Publications Japan
摘要：Long chain alkylcobalamins and long chain acyl-cyanoco-balamins, two types of hydrophobic derivatives of vitamin B12, were synthesized. It was shown by TLC and determination of the partition coefficient between organic and aqueous phases that the hydrophobicity of alkylcobalamins and acyl-cyanocobalamins increased with the chain length of the alkyl or acyl group introduced into cobalamin. Long chain alkylcobalamins were easily converted to aquacobalamin by photoirradia-tion, but the first-order rate constant of photolysis decreased with the length of an alkyl group. Long chain acyl-cyanocobalamins were gradu-ally hydrolyzed to cyanocobalamin in neutral or alkaline solution with the pseudo-first order rate constant increasing with the pH of the solution. Stabilization of acyl-cyanocobalamins toward hydrolysis was achieved by introducing a methyl group into the α-position of an acyl group. All the long chain alkylcobalamins tested supported the growth of Escherichia coli 215, a cobalamin- or L-methionine-auxotroph, and Lactobacillus leichmannii , although their activity as cobalamin was at most 28% and 15% that of cyanocobalamin for E. coli 215 and L. leichmannii , respectively.
