Kinetics of structure and activity changes during the allosteric transition of aspartate transcarbamylase.
For the first time, the structural change associated with an allosteric transition has been monitored by X-ray solution scattering. The kinetics of the quaternary structure change of aspartate transcarbamylase were first slowed by using acetyl phosphate instead of carbamyl phosphate, and by the presence of 10% or 30% ethylene glycol. At 6.5 degrees C, the quaternary structure change was found to have a time constant of about 11 seconds. This appears to be larger than that obtained for the switching of homotropic co-operativity, measured by chemical quench under the same conditions.
Kihara
H
H
Department of Physics, Jichi Medical School, Tochigi-ken, Japan.
Takahashi-Ushijima
E
E
Amemiya
Y
Y
Honda
Y
Y
Vachette
P
P
Tauc
P
P
Barman
T E
TE
Jones
P T
PT
Moody
M F
MF
D000495:Allosteric Site; D001221:Aspartate Carbamoyltransferase; D007700:Kinetics; D046911:Macromolecular Substances; D012542:Scattering, Radiation; D014965:X-Rays
D046911:Macromolecular Substances; D001221:Aspartate Carbamoyltransferase