title: Aspirin interaction with ribonuclease A.
abstract: Aspirin is an anti-inflammatory drug and a main source of protein acetylation that can alter enzymatic activity and protein functions. Ribonuclease A (RNase A) with several high-affinity binding sites is a possible target for many organic and inorganic molecules (Leonidas at al., [2003] Protein Sci. 12, 2559-2574). This study was designed to examine the interaction of aspirin with RNase Aat physiologic conditions. Reaction mixtures of constant protein concentration (3 mM) and different aspirin contents (0.0002-2 mM) are studied by ultraviolet-visible, Fourier transform infrared, and circular dichroism spectroscopic methods to determine the drug binding mode, the drug-binding constant, and the effects of drug complexation on the protein conformation in aqueous solution. Spectroscopic results showed one major binding for the aspirin-RNase complexes with overall binding constant of K = 3.57 x 10(4) M-1. Minor reductions in the protein alpha-helix from 15.5 to 14.1% (circular dichroism) using CDPro program and 26 to 21% (infrared) were observed on aspirin interaction. The changes are indicative of some degree of protein unfolding on drug complexation.
authors.affiliation: Department of Chemistry-Biology, University of Québec at Trois-Rivières, C.P. 500, Trois-Rivières (Québec) Canada G9A 5H7.
authors.forename: J F
authors.initials: JF
authors.lastname: Neault
authors.forename: C
authors.initials: C
authors.lastname: Ragi
authors.forename: A
authors.initials: A
authors.lastname: Novetta-Dellen
authors.forename: H A
authors.initials: HA
authors.lastname: Tajmir-Riahi
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry*; D001241:Aspirin / Q000737:chemistry*; D002417:Cattle; D002942:Circular Dichroism; D017510:Protein Folding; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000893:Anti-Inflammatory Agents; D012259:Ribonuclease, Pancreatic; D001241:Aspirin