title: Combining ultrarapid mixing with photochemical oxidation to probe protein folding.
abstract: We demonstrate a new method to study protein folding by combining fast photochemical oxidation of proteins (FPOP) with ultrarapid microfluidic mixing to observe kinetics on the microsecond time scale. Folding proteins pass through a focused UV laser beam, creating OH radicals that label the select protein side chains and are analyzed with mass spectrometry. As a proof of principle, we demonstrate this method with hen egg lysozyme that shows at least two kinetic phases before 1 ms, which are compared with those observed by Trp fluorescence. This method provides another, complementary probe of the early, complex steps of protein folding.
authors.affiliation: Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, United States.
authors.forename: Ling
authors.initials: L
authors.lastname: Wu
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Lapidus
mesh_terms: D017665:Hydroxyl Radical / Q000737:chemistry; D007700:Kinetics; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D010084:Oxidation-Reduction; D055668:Photochemical Processes; D017510:Protein Folding; D011506:Proteins / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D011506:Proteins; D012997:Solvents; D017665:Hydroxyl Radical