| Summary: | A comparative study of racemic 9-(2,3-dihydroxypropyl)adenine (DHPA) palmitoylation, a potential prodrug, catalysed by several lipases in DMF/co-solvent mixtures and in pure organic solvent was performed. The optimal conditions were investigated as follows: optimal co-solvent mixture, initial aw (water activity), vinyl palmitate/DHPA molar ratio, temperature, enzyme dosage, and chemical modification of biocatalysts. It was shown that an enhancement in the substrate conversion could be achieved with DMF/hexane (4:1) co-solvents as the reaction medium instead of pure organic solvent with immobilized Candida antarctica B (CALB) lipase, although in very low yield. The chemical modification of the lipase had strong positive effect on its activity. The reaction yield was successfully increased (50% after 24 hours) when CALB glycosylated with dextran polymer was used under optimal conditions. The results described further highlight the versatility of lipases and the potential of rational substrate, solvent and enzyme engineering for modulating enzymatic reactions.
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