title: Purification and biochemical characterization of a novel thermostable lipase from Aspergillus niger.
abstract: An extracellular 1,3-specific lipase with molecular weight of 35.5 kDa and an isoelectric point of 4.4 from Aspergillus niger has been purified 50-fold by pH precipitation followed by a series of chromatographic steps with an overall yield of 10%. The enzyme was homogeneous as judged by denaturing polyacrylamide gel electrophoresis and size-exclusion fast-performance liquid chromatography. It contained 2.8% sugar which was completely removed by endoglycosidase F treatment, and the deglycosylated enzyme retained full activity. The native lipase showed optimal activity between temperatures 35 and 55 degrees C and pH 5.0 and 6.0. The amino acid composition and the N-terminal sequence were found to be different from lipases previously purified from A. niger. The enzyme was resistant to trypsin, chymotrypsin, endoprotease Glu-C, thrombin, and papain under native conditions but was susceptible to cleavage by the same proteases when heat-denatured.
authors.affiliation: Department of Biochemistry, Bose Institute, Calcutta, India.
authors.forename: V M
authors.initials: VM
authors.lastname: Namboodiri
authors.forename: R
authors.initials: R
authors.lastname: Chattopadhyaya
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology*; D002845:Chromatography; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D002918:Chymotrypsin / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008049:Lipase / Q000737:chemistry* / Q000302:isolation & purification*; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000494:pharmacology; D010206:Papain / Q000494:pharmacology; D013696:Temperature; D013917:Thrombin / Q000494:pharmacology; D013997:Time Factors; D014357:Trypsin / Q000494:pharmacology
chemical_list: D008049:Lipase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D002918:Chymotrypsin; D014357:Trypsin; D013917:Thrombin; D010206:Papain