comparative study on the substraterecognition was conducted successfully in Novozym 435-mediated acylation of various 2′- or 5-substituted nucleosides with acyl donors carrying different aliphatic chain lengths (C6, C10, and C14). The unexpected results revealed that the physicochemical property of the substituents (such as the size, hydrophobicity, and substitutional position) in nucleosides profoundly influenced
The substraterecognition of Candida antarctica lipase B (CAL-B) in the acylation of nucleosides was revealed through rational substrate engineering for the first time. CAL-B displayed lower activities and excellent 5-regioselectivities (94 to 99 %) in the acylation of ribonucleosides 1f–1j as compared to those in the acylation of 2-deoxynucleosides 1a– 1e. The excellent regioselectivities might be
The activity of porcine liver esterase towards diesters of 5-fluoro-2'-deoxyuridine with saturated aliphatic acids including acetic, propionic, butyric, hexanoic, octanoic, decanoic and dodecanoic acids was investigated. The susceptibility of the 3', 5'-diesters increased as the acyl chain was lengthened up to octanoyl, but further increase in the acyl chain length resulted in a sharp decrease in the susceptibility. The susceptibility of 3'-and 5'-monoesters increased as the chain was lengthened to decanoyl and slightly decreased on going to dodecanoyl. These results suggest that the higher antitumor activity of longer alkyl chain diesters of 5-fluoro-2'-deoxyuridine is partly due to their slow rates of hydrolysis by non-specific esterase.