title: Changes in PLA(2) activity after interacting with anti-inflammatory drugs and model membranes: evidence for the involvement of tryptophan residues.
abstract: Phospholipase A(2) (PLA(2)) 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 PLA(2) 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 PLA(2) tryptophan residues was further used to gain complementary information regarding the accessibility of these residues on the PLA(2) structure upon interaction with the NSAIDs tested; and to calculate the NSAIDs-PLA(2) binding constants. Finally, circular dichroism (CD) measurements were performed to evaluate changes in PLA(2) 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 PLA(2) 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.
authors: REQUIMTE, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua Aníbal Cunha, Porto, Portugal.
authors: Diana
authors: D
authors: Gaspar
authors: Marlene
authors: M
authors: Lúcio
authors: Sandra
authors: S
authors: Rocha
authors: J L F Costa
authors: JL
authors: Lima
authors: Salette
authors: S
authors: Reis
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D055162:Biocatalysis / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004546:Elapid Venoms / Q000201:enzymology; D017815:Elapidae; D006868:Hydrolysis / Q000187:drug effects; D008567:Membranes, Artificial; D008958:Models, Molecular; D064801:Phospholipase A2 Inhibitors; D054467:Phospholipases A2 / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004546:Elapid Venoms; D008567:Membranes, Artificial; D064801:Phospholipase A2 Inhibitors; D014364:Tryptophan; D054467:Phospholipases A2