Novel minor lipase from Rhizopus chinensis during solid-state fermentation: Biochemical characterization and its esterification potential for ester synthesis
2009
Sun, Shu Yang | Xu, Yan | Wang, Dong
Rhizopus chinensis produces two lipases that catalyze ester synthesis when cultured under solid-state fermentation. The Lip2 was purified to homogeneity by ammonium sulphate precipitation, hydrophobic interaction chromatography and gel filtration chromatography. It has an apparent molecular weight of 33kDa estimated from SDS-PAGE and 32kDa calculated from analytical gel permeation, with synthetic activity and purification fold of 96.8U/mg and 138.3, respectively. Maximum hydrolytic activity was obtained at pH 8.0-8.5 and 40°C using pNPP as substrate. Slight activation of the enzyme was observed when Mn²⁺ is present. The enzyme was most active on p-nitrophenyl laurate (C12). The purified lipase exhibited maximum synthetic activity at pH memory of 6.0 and 30 oC. Most of ethyl esters synthesized by lyophilized enzyme achieved good yields (>90%), and caprylic acid served as the best acyl donor. The enzyme presented a particular affinity for ethanol, n-propanol and n-hexanol, with conversion of 92%, 93% and 92%, respectively, after 20h incubation.
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