Kinetic study on the dimer-tetramer interconversion of phosphorylase b by a stopped-flow X-ray scattering method.
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.
Wang
Z X
ZX
Jichi Medical School, School of Nursing, Tochigi, Japan.
Tsuruta
H
H
Honda
Y
Y
Tachi-iri
Y
Y
Wakabayashi
K
K
Amemiya
Y
Y
Kihara
H
H
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
D046911:Macromolecular Substances; D010763:Phosphorylase b; D006005:Phosphorylases