title: Kinetic study on the dimer-tetramer interconversion of phosphorylase b by a stopped-flow X-ray scattering method.
abstract: The dimer-tetramer interconversion of phosphorylase b induced by the binding of AMP and Mg2+ was monitored using a stopped-flow X-ray scattering method. The rate constants of this second-order reaction have been determined by a nonlinear least-squares method. Burst phases in both radii of gyration and zero-angle intensities were detected at the initial step of the reaction. This suggests that rapid association might take place, followed by a slow association process of which the kinetics were measured in the present study. The radius of gyration of tetrameric phosphorylase b was determined and found to be in excellent agreement with that of phosphorylase a, but different from that of phosphorylase b reported elsewhere (G. Puchwein, O. Kratky, C. F. Golker and E. Helmreich, Biochemistry 9 (1970) 4691). The reason for this inconsistency is discussed.
authors.affiliation: Jichi Medical School, School of Nursing, Tochigi, Japan.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Wang
authors.forename: H
authors.initials: H
authors.lastname: Tsuruta
authors.forename: Y
authors.initials: Y
authors.lastname: Honda
authors.forename: Y
authors.initials: Y
authors.lastname: Tachi-iri
authors.forename: K
authors.initials: K
authors.lastname: Wakabayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Amemiya
authors.forename: H
authors.initials: H
authors.lastname: Kihara
mesh_terms: D000818:Animals; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D009132:Muscles / Q000201:enzymology; D010763:Phosphorylase b / Q000378:metabolism*; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D012542:Scattering, Radiation / Q000379:methods; D014965:X-Rays
chemical_list: D046911:Macromolecular Substances; D010763:Phosphorylase b; D006005:Phosphorylases