title: Purification and biochemical characterization of a secreted group IIA chicken intestinal phospholipase A₂.
abstract: BACKGROUND
  Secretory phospholipase A2 group IIA (IIA PLA2) is a protein shown to be highly expressed in the intestine of mammals. However, no study was reported in birds.
  
  
  RESULTS
  Chicken intestinal group IIA phospholipase A₂ (ChPLA₂-IIA) was obtained after an acidic treatment (pH.3.0), precipitation by ammonium sulphate, followed by sequential column chromatographies on Sephadex G-50 and mono-S ion exchanger. The enzyme was found to be a monomeric protein with a molecular mass of around 14 kDa. The purified enzyme showed a substrate preference for phosphatidylethanolamine and phosphatidylglycerol, and didn't hydrolyse phosphatidylcholine. Under optimal assay conditions, in the presence of 10 mM NaTDC and 10 mM CaCl₂, a specific activity of 160 U.mg⁻¹ for purified ChPLA₂-IIA was measured using egg yolk as substrate. The fifteen NH2-terminal amino acid residues of ChPLA₂-IIA were sequenced and showed a close homology with known intestinal secreted phospholipases A₂. The gene encoding the mature ChPLA₂-IIA was cloned and sequenced. To further investigate structure-activity relationship, a 3D model of ChPLA₂-IIA was built using the human intestinal phospholipase A₂ structure as template.
  
  
  CONCLUSIONS
  ChPLA2-IIA was purified to homogeneity using only two chromatographic colomns. Sequence analysis of the cloned cDNA indicates that the enzyme is highly basic with a pI of 9.0 and has a high degree of homology with mammalian intestinal PLA₂-IIA.
authors.affiliation: Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS Route de Soukra, 3038 Sfax, University of Sfax, Tunisia.
authors.forename: Aida
authors.initials: A
authors.lastname: Karray
authors.forename: Fakher
authors.initials: F
authors.lastname: Frikha
authors.forename: Yassine
authors.initials: Y
authors.lastname: Ben Ali
authors.forename: Youssef
authors.initials: Y
authors.lastname: Gargouri
authors.forename: Sofiane
authors.initials: S
authors.lastname: Bezzine
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001647:Bile Acids and Salts / Q000737:chemistry; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002645:Chickens; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D057075:Enzyme Assays; D004795:Enzyme Stability; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D054467:Phospholipases A2 / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid
chemical_list: D001647:Bile Acids and Salts; D004247:DNA; D054467:Phospholipases A2; D002118:Calcium