Purification, characterization, and cDNA cloning of acidic platelet aggregation inhibiting phospholipases A sub(2) from the snake venom of Vipera lebetina (Levantine viper)

• Published in: Toxicon (Oxford) 2009-09, Vol.54 (4), p.429-439
• Main Authors: Vija, H, Samel, M, Siigur, E, Aaspollu, A, Trummal, K, Tonismagi, K, Subbi, J, Siigur, J
• Format: Article
• Language: English
• Subjects: Vipera lebetina
• ISSN: 0041-0101
• DOI: 10.1016/j.toxicon.2009.05.010

Two novel acidic phospholipase A sub(2)s (PLA sub(2)) were isolated by size exclusion chromatography and reversed-phase chromatography from the crude Vipera lebetina venom. The molecular masses of VLPLA sub(2)-1 (13,704Da) and VLPLA sub(2)-2 (13,683Da) and their internal tryptic peptides were determined by MALDI-TOF mass-spectrometry. When tested in human platelet-rich plasma, both enzymes showed a potent inhibitory effect on aggregation induced by ADP and collagen. Chemical modification with p-bromophenacylbromide abolished the enzymatic activity of PLA sub(2); its anti-platelet activity was fully inhibited in case of collagen as inducer and partially inhibited in case of ADP as inducer. The complete cDNAs encoding PLA sub(2) were cloned from a single venom gland cDNA library. Complete amino acid sequences of the VLPLA sub(2) were deduced from the cDNA sequences. The full-length cDNA sequences of the VLPLA sub(2) possess 615bp and encode an open reading frame of 138 amino acids that include signal peptide (16 amino acids) and mature enzyme (122 amino acids). The VLPLA sub(2)s have significant sequence similarity to many other phospholipase A sub(2)s from snake venoms. The phylogenetic analysis on the basis of the amino acid sequence homology demonstrates that VLPLA sub(2)s grouped with other Asp49 PLA sub(2)s and they appear to share a close evolutionary relationship with the European vipers. time-of-flight mass spectrometry