Rees G D, Robinson B H, Stephenson G R
School of Chemical Sciences, University of East Anglia, Norwich, Norfolk, UK.
Biochim Biophys Acta. 1995 Aug 3;1257(3):239-48. doi: 10.1016/0005-2760(95)00084-p.
Five microbial lipases from Chromobacterium viscosum, Candida cylindracea, Pseudomonas (source Fluka), Pseudomonas (source Genzyme) and lipoprotein lipase ex Microbial (Genzyme) have been screened for lactonisation activity towards 16-hydroxyhexadecanoic acid (HHA) in a variety of different w/o microemulsion systems. With the exception of Candida cylindracea (CC), all the lipases exhibited lactonisation activity although they were inherently more active in microemulsion systems based on the anionic surfactant sodium bis(2-ethylhexyl)sulphosuccinate (AOT) than in those based on the cationic surfactant cetyltrimethylammonium bromide (CTAB). Lactone yields are typically 50-60% and are markedly better than those reported previously using microemulsions in combination with chemical catalysts. Lipase stability is superior in the CTAB microemulsion systems, while lipase stability in the low water content AOT microemulsion systems was still good with the exception of CC lipase, which is rapidly inactivated. Buffering the water pools of AOT microemulsions using diglycine buffer at pH 8.0 improved biocatalyst stability. The lactonisation activity of lipases in CTAB w/o microemulsion systems compares favourably with that obtained using the same preparations as a solid suspension in the corresponding water-saturated organic solvent. In addition, the unusual solubility properties of microemulsions allowed the use of considerably higher concentrations of substrate in the microemulsion systems as compared to water-saturated organic solvents such as n-heptane. Lactone yields obtained at equivalent concentrations in the corresponding organic solvents containing conventional condensation catalysts were consistently measured at approx. 10%.
对来自粘质沙雷氏菌、柱形假丝酵母、假单胞菌（来源为Fluka）、假单胞菌（来源为Genzyme）以及微生物脂蛋白脂肪酶（Genzyme）的五种微生物脂肪酶，在多种不同的水包油型微乳液体系中，针对16-羟基十六烷酸（HHA）的内酯化活性进行了筛选。除柱形假丝酵母（CC）外，所有脂肪酶均表现出内酯化活性，尽管它们在基于阴离子表面活性剂双（2-乙基己基）磺基琥珀酸钠（AOT）的微乳液体系中，比在基于阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）的微乳液体系中，固有活性更高。内酯产率通常为50%-60%，明显优于先前报道的使用微乳液与化学催化剂结合的产率。脂肪酶在CTAB微乳液体系中的稳定性更佳，而在低含水量的AOT微乳液体系中，除CC脂肪酶会迅速失活外，其他脂肪酶的稳定性依然良好。使用pH 8.0的二甘氨酸缓冲液对AOT微乳液的水池进行缓冲，可提高生物催化剂的稳定性。脂肪酶在CTAB水包油型微乳液体系中的内酯化活性，与在相应水饱和有机溶剂中作为固体悬浮液使用相同制剂所获得的活性相当。此外，微乳液不同寻常的溶解特性使得在微乳液体系中能够使用浓度远高于水饱和有机溶剂（如正庚烷）的底物。在含有传统缩合催化剂的相应有机溶剂中，在等效浓度下测得的内酯产率始终约为10%。
