title: Purification and characterization of a hydrolysis-resistant lipase from Aspergillus terreus.
abstract: Lipase from Aspergillus terreus was purified to homogeneity using ammonium sulfate precipitation and chromatographies with Q-Sepharose and Sephacryl S-200. It showed a single band on SDS-PAGE and IEF-PAGE with a relative molecular mass of 37.2 kDa and pI of 3.2. Its glycoprotein nature was confirmed with the percentage of saccharides of 5.02% and 3.88% determined by the phenol/sulfuric acid and anthrone/ sulfuric acid methods, respectively. The lipase hydrolyzed both plant oils and animal oils, with the K(m) value for substrate p-NPP of 16.42 mM at pH 6.0, 50 °C. The enzyme was tolerant in a wide range of pH (pH 3-12) with optimum activity at pH 4.0. It remained stable under the highest temperature of 65 °C, with maximal activity at 50 °C. Ca²⁺, Co²⁺, Mn²⁺, and Ni²⁺ stimulated enzyme activity, but Hg²⁺ caused inhibition. Detected detergents had no obvious effect on enzyme activity, except SDS, which stimulated the activity at lower concentrations but inhibited the activity at higher concentrations. The inhibitory effect on enzyme activity of phenylmethanesulfonyl fluoride revealed that the Ser was involved in catalysis. Saccharides had no obvious effect on enzyme activity but could enhance its thermostability. Furthermore, the enzyme was resistant to trypsin digestion.
authors.affiliation: Key Laboratory of Bio-Resources and Eco-Environment, Ministry of Education/Animal Disease Prevention and Food Safety, Key Laboratory of Sichuan Province, College of Life Science, Sichuan University, Chengdu, Sichuan, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Shi
authors.forename: Yao
authors.initials: Y
authors.lastname: Meng
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.forename: Qinglian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yanfa
authors.initials: Y
authors.lastname: Meng
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006868:Hydrolysis; D008049:Lipase / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D014357:Trypsin / Q000737:chemistry
chemical_list: D008049:Lipase; D014357:Trypsin
keywords: Aspergillus terreus; characteristics; lipase; purification