title: Effects of pH on kinetics of binding of mRNA-cap analogs by translation initiation factor eIF4E.
abstract: Stopped-flow spectrofluorimetry and a theoretical method for predicting protonation equilibria in polyelectrolytes were combined in an analysis of the pH dependence of the kinetics of binding of analogues of the 5'-mRNA cap to the cap binding protein eIF4E. The computer simulations and available experimental data indicate that there are two titratable groups in the binding site of the protein and two titratable groups on the ligands directly involved in the binding, in addition to stacking interactions described by other groups. The observed pH dependencies of the rate constants obtained from the stopped-flow experiments are consistent with this finding. In particular, it is concluded that binding of both forms of the cap analogs regarding protonation at the N1 position of the guanine ring is efficient, and the shift to a predominantly protonated form of the ring takes place after formation of the complex.
authors.affiliation: Department of Biophysics, Warsaw University, Warsaw 02-089, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Długosz
authors.forename: E
authors.initials: E
authors.lastname: Błachut-Okrasińska
authors.forename: E
authors.initials: E
authors.lastname: Bojarska
authors.forename: E
authors.initials: E
authors.lastname: Darzynkiewicz
authors.forename: J M
authors.initials: JM
authors.lastname: Antosiewicz
mesh_terms: D000818:Animals; D003198:Computer Simulation; D003461:Crystallography / Q000379:methods; D004563:Electrochemistry / Q000379:methods; D039561:Eukaryotic Initiation Factor-4E / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D046911:Macromolecular Substances; D051379:Mice; D008956:Models, Chemical; D008958:Models, Molecular; D011485:Protein Binding; D012314:RNA Cap Analogs / Q000737:chemistry*; D012333:RNA, Messenger / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D055672:Static Electricity
chemical_list: D039561:Eukaryotic Initiation Factor-4E; D046911:Macromolecular Substances; D012314:RNA Cap Analogs; D012333:RNA, Messenger