title: Unveiling the timescale of the R-T transition in human hemoglobin.
abstract: Time-resolved wide-angle X-ray scattering, a recently developed technique allowing to probe global structural changes of proteins in solution, was used to investigate the kinetics of R-T quaternary transition in human hemoglobin and to systematically compare it to that obtained with time-resolved optical spectroscopy under nearly identical experimental conditions. Our data reveal that the main structural rearrangement associated with the R-T transition takes place approximately 2 mus after the photolysis of hemoglobin at room temperature and neutral pH. This finding suggests that the 20-mus step observed with time-resolved optical spectroscopy corresponds to a small and localized structural change.
authors.affiliation: European Synchrotron Radiation Facility, Grenoble, France.
authors.forename: M
authors.initials: M
authors.lastname: Cammarata
authors.forename: M
authors.initials: M
authors.lastname: Levantino
authors.forename: M
authors.initials: M
authors.lastname: Wulff
authors.forename: A
authors.initials: A
authors.lastname: Cupane
mesh_terms: D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010777:Photochemistry; D011487:Protein Conformation; D012542:Scattering, Radiation; D013057:Spectrum Analysis
chemical_list: D006454:Hemoglobins