title: Protein and cDNA structures of an acidic phospholipase A2, the enzymatic part of an unusual, two-component toxin from Vipera palaestinae.
abstract: In the venom of Vipera palaestinae an unusual, two-component toxin was found. The two components of the toxin are an acidic phospholipase A2 (VpaPLA2) and a basic protein, both with an apparent molecular mass of about 15 kDa. Each component alone is not toxic; however, their mixture is lethal. We have determined the amino acid and cDNA sequences of VpaPLA2. The protein primary structure was solved by sequencing the peptides generated by chemical cleavage of the molecule using CNBr, formic acid and hydroxylamine-hydrochloride and by enzymatic fragmentation with trypsin and chymotrypsin. VpaPLA2 consists of 122 amino acid residues and has all the structural characteristics of subgroup IIA PLA2s. It shows the highest amino acid similarity to a non-toxic phospholipase A2 from Eristocophis macmahoni (82%), whereas the most similar toxic phospholipases A2 share about 70% of residues with VpaPLA2. The substitution of His20 for a hydrophobic residue (Leu) in VpaPLA2 might be one of the reasons that its complex with the basic protein could not be observed.
authors.affiliation: Department of Biochemistry and Molecular Biology, Jozef Stefan Institute, Jamova, Ljubljana, Slovenia. igor.krizaj@ijs.si
authors.forename: I
authors.initials: I
authors.lastname: Krizaj
authors.forename: A
authors.initials: A
authors.lastname: Bdolah
authors.forename: F
authors.initials: F
authors.lastname: Gubensek
authors.forename: P
authors.initials: P
authors.lastname: Bencina
authors.forename: J
authors.initials: J
authors.lastname: Pungercar
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002918:Chymotrypsin; D017931:DNA Primers; D018076:DNA, Complementary / Q000737:chemistry* / Q000378:metabolism; D007202:Indicators and Reagents; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D010449:Peptide Mapping; D010741:Phospholipases A / Q000096:biosynthesis / Q000737:chemistry*; D054467:Phospholipases A2; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D014357:Trypsin; D014757:Viper Venoms; D017819:Viperidae
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D007202:Indicators and Reagents; D010446:Peptide Fragments; D011994:Recombinant Proteins; D014757:Viper Venoms; D010741:Phospholipases A; D054467:Phospholipases A2; D002918:Chymotrypsin; D014357:Trypsin