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Biochemical and molecular characterization of a lipase from an Algerian isolated Staphylococcus aureus strain
Author(s) -
Nehal Fatima,
Jallouli Raida,
Krayem Najeh,
Bou Ali Madiha,
Dilmi Bouras Abdelkader,
Fendri Ahmed,
Gargouri Youssef
Publication year - 2017
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201600462
Subject(s) - lipase , staphylococcus aureus , biochemistry , tributyrin , isoleucine , valine , triacylglycerol lipase , chemistry , enzyme , amino acid , biology , chromatography , leucine , bacteria , genetics
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 −1 using 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 ( π c ) 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.