| Summary: | 碩士 === 國立東華大學 === 化學研究所 === 88 === Abstract
Enzyme catalyzed hydrolysis is an efficient way to resolve racemic compounds. In many cases, the enantioselectivity of an enzymatic reaction is relied on the high purity of enzyme. Therefore, a systematic study of hydrolysis of ibuprofen and ketoprofen esters catalyzed by different fractions from separation of commercial lipase OF was carried out. We identified two isozymes (lipase OF I, lipase OF II) after lipase OF was passed through a mercurial affinity column with phosphate buffer. Subsequently, the binded mercaptoprotein (lipase OF III) was flushed out with cystine solution. These purified isozymes not only demonstrated powerful ability to differentiate between enantiomers of a-methyl-carboxylic acid, but also showed a significant difference in the enantioselectivity between those isozymes under different pH condition. Lipase OF I exhibited the optimized condition at neutral pH ( pH = 6 ~7 ) while lipase OF II gave the highest resolution at acidic conditions ( pH = 2.6 ~ 3.0 ). As for lipase OF III, it showed an opposite enantio-preference at slightly basic environment ( pH = 7.5 ~ 8.0 ).
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