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KMID : 1094720100150040608
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Biotechnology and Bioprocess Engineering
2010 Volume.15 No. 4 p.608 ~ p.613
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Application of organic solvent system for lipase-catalyzed regioselective benzoylation of 1-β-D-arabinofuranosylcytosine
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Li Xiao-Feng
Zong Min-Hua
Zhao Guang-Lei
Yu Yi-Gang
Wu Hui
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Abstract
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In this paper, enzymatic regioselective acylation of 1-β-D-arabinofuranosylcytosine (ara-C) with vinyl benzoate (VB) using immobilized Candida antarctica lipase B in binary organic solvents was explored. It was found that the lipase showed high regioselectivity (> 99%) towards the 5′-OH of ara-C in the representative organic solvent mixture (hexane-pyridine). To understand the enzymatic processes and provide a fair comparison of hexane-pyridine with C4MIm·PF6-pyridine (the representative ionic liquid-containing system), the effect of each process variable on the reactions in hexane-pyridine was investigated. The results indicate that the optimum hexane content, initial a w , molar ratio of VB to ara-C, and temperature were 28% (v/v), 0.11, 15, and 40°C, respectively. Under optimized conditions, the initial reaction rate in hexanepyridine (44.4 mM/h) was much higher than that in C4MIm·PF6-pyridine (29.4 mM/h) for each case. The maximum conversion yield, however, was increased when the reaction system was shifted from hexane-pyridine to C4MIm·PF6-pyridine. Further study revealed that the presence of an acidic by-product (benzoate acid, released during the acylation process) may cause rapid inactivation of the enzyme in hexane-pyridine, leading to a lower conversion rate, whereas the ionic liquid may have coating and protecting effects on the lipase during the reaction.
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KEYWORD
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1-β-D-arabinofuranosylcytosine, biocatalysis, organic solvent, benzoylation
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