title: Enzymatic properties of stingray Dasyatis pastinaca group V, IIA and IB phospholipases A(2): a comparative study.
abstract: In the present study, we have purified the group V phospholipase from the heart of cartilaginous fish stingray Dasyatis pastinaca and compared its biochemical properties with group IIA (sPLA2-IIA) and IB (sPLA2-IB) phospholipases previously purified from pancreas and intestine, respectively. Group V phospholipase (sPLA2-V) was purified to homogeneity by heat treatment, ammonium sulphate precipitation and RP-HPLC. The N-terminal sequence of the purified sPLA2-V exhibits a high degree of homology with those of mammal. The enzyme was found to be monomeric with a molecular mass estimation of 14 kDa. The specific activity of the purified enzyme, measured at pH 8 and 37 °C was 52 U/mg. Like sPLA2-IB and sPLA2-IIA, the sPLA2-V is found to be stable between pH 3 and 11 after 30 min of incubation. The purified sPLA2-V retained 65% of its activity after 10 min of incubation at 70 °C and it absolutely requires Ca(2+) for enzymatic activity. In addition it displayed high tolerance to organic solvents. Kinetic parameters Kmapp, kcat and the deduced catalytic efficiency (kcat/Kmapp) of the purified group-V, -IB and -IIA PLA2s were determined using phosphatidylethanolamine (PE), phosphatidylcholine (PC) or phosphatidylserine (PS) as substrate. The three enzymes hydrolyze the zwiterionic PE and PC substrates more efficiently than anionic PS substrate.
authors.affiliation: Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia; Laboratory of Plant Biotechnology Applied to Crop Improvement, Faculty of Science of Sfax, University of Sfax, Sfax 3038, Tunisia. Electronic address: abirghanouchibenbacha@yahoo.fr.
authors.forename: Abir
authors.initials: A
authors.lastname: Ben Bacha
authors.forename: Islem
authors.initials: I
authors.lastname: Abid
authors.forename: Habib
authors.initials: H
authors.lastname: Horchani
authors.forename: Hafedh
authors.initials: H
authors.lastname: Mejdoub
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology; D002118:Calcium / Q000737:chemistry / Q000494:pharmacology; D018940:Elasmobranchii / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D054500:Group IB Phospholipases A2 / Q000737:chemistry / Q000378:metabolism*; D054501:Group II Phospholipases A2 / Q000737:chemistry / Q000378:metabolism*; D054505:Group V Phospholipases A2 / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D012997:Solvents; D013379:Substrate Specificity; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D001647:Bile Acids and Salts; D012997:Solvents; D054500:Group IB Phospholipases A2; D054501:Group II Phospholipases A2; D054505:Group V Phospholipases A2; D014357:Trypsin; D002118:Calcium
keywords: Characterization; Kinetics; Phospholipases A(2) group-V, -IIA, -IB; Purification; Stingray Dasyatis pastinaca