title: Biochemical and molecular characterization of a lipase from an Algerian isolated Staphylococcus aureus strain.
abstract: A Staphylococcus aureus strain, isolated from an Algerian biotope, secretes a non-induced lipase in the culture medium. The S. aureus lipase (SAL) was purified to homogeneity. Pure SAL is a monomeric protein (43 kDa). The 20 N-terminal amino acid residues showed a high degree of homology with other staphylococcal lipase sequences. SAL presents specific activities of about 1600 and 555 U mg-1using tributyrin and olive oil emulsion as substrates, respectively. In contrast to other staphylococcal lipases previously characterized, SAL was stable at a pH range from 6 to 9 after 1 h incubation, and retained 50% of its activity after 10 min incubation at 50 °C. The purified enzyme was also characterized using monolayer technique. Lipase activity can be measured only when the surface pressure exceeds 15 mN m-1. The critical surface pressure (πc) measured with egg-PC films was estimated at 33 mN m-1. SAL showed a preference for the distal ester groups of the diglyceride isomers at low surface pressure, for the adjacent ester groups at high surface pressure and a preference for the sn-3 position of the 2,3-sn-enantiomer of dicaprin. Cloned and sequenced gene part, encoding the mature lipase shows, in comparison with S. aureus lipase 3 (SAL3), a deletion of three residues (LKA) at the N-terminal extremity and a substitution of glycine 208 and isoleucine 226 with an arginine and leucine, respectively.
authors.affiliation: Laboratoire Bio-ressources Naturelles Locales, Faculté des Sciences de la Nature et de la Vie, Université Hassiba Ben Bouali, Chlef, Algeria.|Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Fatima
authors.initials: F
authors.lastname: Nehal
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Raida
authors.initials: R
authors.lastname: Jallouli
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Najeh
authors.initials: N
authors.lastname: Krayem
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Madiha
authors.initials: M
authors.lastname: Bou Ali
authors.affiliation: Laboratoire Bio-ressources Naturelles Locales, Faculté des Sciences de la Nature et de la Vie, Université Hassiba Ben Bouali, Chlef, Algeria.
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Dilmi Bouras
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Fendri
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, Université de Sfax, ENIS route de Soukra, Sfax, Tunisia.
authors.forename: Youssef
authors.initials: Y
authors.lastname: Gargouri
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D004655:Emulsions; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008049:Lipase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D000069463:Olive Oil / Q000378:metabolism; D011312:Pressure; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity; D013501:Surface-Active Agents / Q000737:chemistry / Q000302:isolation & purification; D014280:Triglycerides / Q000378:metabolism
chemical_list: D003470:Culture Media; D004655:Emulsions; D000069463:Olive Oil; D013501:Surface-Active Agents; D014280:Triglycerides; D008049:Lipase; C005830:tributyrin
keywords: Baro-stat; Staphylococcus aureus lipase; pH-stat; regioselectivity; stereoselectivity