Functional site of endogenous phospholipase A2 inhibitor from python serum.
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.
Thwin
Maung-Maung
MM
Venom and Toxin Research Programme, Department of Anatomy, Faculty of Medicine, National University of Singapore, Singapore.
Satish
Ramapatna L
RL
Chan
Steven T F
ST
Gopalakrishnakone
Ponnampalam
P
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
D000893:Anti-Inflammatory Agents; D004791:Enzyme Inhibitors; D009842:Oligopeptides; C449660:P-PB.III peptide; D010741:Phospholipases A; D054467:Phospholipases A2