Changes in PLA₂ activity after interacting with anti-inflammatory drugs and model membranes: evidence for the involvement of tryptophan residues

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• 作者：Diana Gaspar^a ; Marlene Lú ; cio^a ; Sandra Rocha^b ; J.L.F. Costa Lima^a ; Salette Reis^a ; ^{shreis@ff.up.pt"" rel=""nofollow}
• 关键词：Liposomes ; NSAIDs ; PLA₂ inhibition ; ADIFAB ; Tryptophan fluorescence quenching and circular dichroism
• 刊名：Chemistry and Physics of Lipids
• 出版年：2011
• 出版时间：May 2011
• 年：2011
• 卷：164
• 期：4
• 页码：292-299
• 全文大小：494 K

文摘

Phospholipase A₂ (PLA₂) lipolytic activity can be regarded as a limiting factor for the development of inflammatory processes by restricting the production of pro-inflammatory mediators, hence representing a valuable therapeutic target for drugs that are able to modulate the activity of this enzyme. In the current work, the hydrolysis of phospholipids by PLA₂ was monitored with acrylodan-labelled intestinal fatty acid binding protein (ADIFAB) and this fluorescence based technique was also used to access the enzymatic inhibitory effect of non-steroidal anti-inflammatory drugs (NSAIDs). The intrinsic fluorescence of PLA₂ tryptophan residues was further used to gain complementary information regarding the accessibility of these residues on the PLA₂ structure upon interaction with the NSAIDs tested; and to calculate the NSAIDs-PLA₂ binding constants. Finally, circular dichroism (CD) measurements were performed to evaluate changes in PLA₂ conformation resultant from the inhibitory effect of the drugs tested. Overall, results gathered in this study point to the conclusion that the studied NSAIDs inhibit PLA₂ activity due to a disturbance of the enzyme binding efficiency to membrane interface possibly by a shielding effect of the Trp residues required for the membrane interfacial binding step that precedes lipolysis process.