title: Stopped-flow x-ray scattering: the dissociation of aspartate transcarbamylase.
abstract: A combination of stopped-flow and x-ray scattering techniques was used to study the dissociation of aspartate transcarbamylase (carbamoylphosphate:L-aspartate carbamoyltransferase, EC 2.1.3.2) with a 2:1 excess of p-chloromercuribenzenesulfonic acid (the ratio being calculated on a basis of reactive sites), in the presence and absence of the transition state analogue N-(phosphonacetyl)-L-aspartate. At 10 mg of protein per ml, the scattering curves allowed some details of the reaction to be followed with a time resolution down to 1 sec. The curves showed not only the dissociation of the enzyme complex but also the formation of the subunits. These results show that, with present facilities, x-ray scattering could be used to study dissociation or reassociation reactions with a time resolution of the order of 100 msec.
mesh_terms: D000494:Allosteric Regulation; D001221:Aspartate Carbamoyltransferase / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D011485:Protein Binding; D012542:Scattering, Radiation; D014965:X-Rays
chemical_list: D046911:Macromolecular Substances; D001221:Aspartate Carbamoyltransferase