title: Functional site of endogenous phospholipase A2 inhibitor from python serum.
abstract: The functional site of 'phospholipase A2 inhibitor from python' (PIP) was predicted based on the hypothesis of proline brackets. Using different sources of secretory phospholipase A2 (sPLA2s) as enzyme, and [3H]arachidonate-labelled Escherichia coli as substrate, short synthetic peptides representing the proposed site were examined for their secretory phospholipase A2 (sPLA2) inhibitory activity. A decapeptide P-PB.III proved to be the most potent of the tested peptides in inhibiting sPLA2 enzymatic activity in vitro, and exhibited striking anti-inflammatory effects in vivo in a mouse paw oedema model. P-PB.III inhibited the enzymatic activity of class I, II and III PLA2s, including that of human synovial fluid from arthritis patients. When tested by ELISA, biotinylated P-PB.III interacted positively with various PLA2s, suggesting that the specific region of PIP corresponding to P-PB.III, is likely to be involved in the PLA2-PLI interaction. The effect of P-PB.III on the peritoneal inflammatory response after surgical trauma in rats was also examined. P-PB.III effectively reduced the extent of postsurgical peritoneal adhesions as compared to controls. sPLA2 levels at seventh postoperative day in the peritoneal tissue of P-PB.III-treated rats were also significantly reduced (P < 0.05) in comparison to those of the untreated controls. The present results shed additional insight on the essential structural elements for PLA2 binding, and may be useful as a basis for the design of novel therapeutic agents.
authors.affiliation: Venom and Toxin Research Programme, Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore.
authors.forename: Maung-Maung
authors.initials: MM
authors.lastname: Thwin
authors.forename: Ramapatna L
authors.initials: RL
authors.lastname: Satish
authors.forename: Steven T F
authors.initials: ST
authors.lastname: Chan
authors.forename: Ponnampalam
authors.initials: P
authors.lastname: Gopalakrishnakone
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology; D017821:Boidae / Q000097:blood*; D004791:Enzyme Inhibitors / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000097:blood* / Q000378:metabolism / Q000494:pharmacology; D010741:Phospholipases A / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054467:Phospholipases A2; D017386:Sequence Homology, Amino Acid
chemical_list: D000893:Anti-Inflammatory Agents; D004791:Enzyme Inhibitors; D009842:Oligopeptides; C449660:P-PB.III peptide; D010741:Phospholipases A; D054467:Phospholipases A2