title: Gemini surfactants affect the structure, stability, and activity of ribonuclease Sa.
abstract: Gemini surfactants have important advantages, e.g., low micromolar CMCs and slow millisecond monomer ↔ micelle kinetics, for membrane mimetics and for delivering nucleic acids for gene therapy or RNA silencing. However, as a prerequisite, it is important to characterize interactions occurring between Gemini surfactants and proteins. Here NMR and CD spectroscopies are employed to investigate the interactions of cationic Gemini surfactants with RNase Sa, a negatively charged ribonuclease. We find that RNase Sa binds Gemini surfactant monomers and micelles at pH values above 4 to form aggregates. Below pH 4, where the protein is positively charged, these aggregates dissolve and interactions are undetectable. Thermal denaturation experiments show that surfactant lowers RNase Sa's conformational stability, suggesting that surfactant binds the protein's denatured state preferentially. Finally, Gemini surfactants were found to bind RNA, leading to the formation of large complexes. Interestingly, Gemini surfactant binding did not prevent RNase Sa from cleaving RNA.
authors.affiliation: Department of Chemistry, University of Isfahan , Isfahan 81746-73441, Iran.
authors.forename: Razieh
authors.initials: R
authors.lastname: Amiri
authors.forename: Abdol-Khalegh
authors.initials: AK
authors.lastname: Bordbar
authors.forename: Douglas V
authors.initials: DV
authors.lastname: Laurents
mesh_terms: D002412:Cations / Q000737:chemistry; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D011489:Protein Denaturation; D055550:Protein Stability; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012313:RNA / Q000737:chemistry; D059367:RNA Cleavage; D012260:Ribonucleases / Q000737:chemistry*; D055672:Static Electricity; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature
chemical_list: D002412:Cations; D008823:Micelles; D000644:Quaternary Ammonium Compounds; D013501:Surface-Active Agents; D012313:RNA; D012260:Ribonucleases; C077002:ribonuclease Sa3