title: Trapping and structure determination of an intermediate in the allosteric transition of aspartate transcarbamoylase.
abstract: X-ray crystallography and small-angle X-ray scattering (SAXS) in solution have been used to show that a mutant aspartate transcarbamoylase exists in an intermediate quaternary structure between the canonical T and R structures. Additionally, the SAXS data indicate a pH-dependent structural alteration consistent with either a pH-induced conformational change or a pH-induced alteration in the T to R equilibrium. These data indicate that this mutant is not a model for the R state, as has been proposed, but rather represents the enzyme trapped along the path of the allosteric transition between the T and R states.
authors.affiliation: Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, MA 02467, USA.
authors.forename: Wenyue
authors.initials: W
authors.lastname: Guo
authors.forename: Jay M
authors.initials: JM
authors.lastname: West
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Dutton
authors.forename: Hiro
authors.initials: H
authors.lastname: Tsuruta
authors.forename: Evan R
authors.initials: ER
authors.lastname: Kantrowitz
mesh_terms: D000494:Allosteric Regulation; D001221:Aspartate Carbamoyltransferase / Q000737:chemistry* / Q000235:genetics; D002852:Chromatography, Ion Exchange; D003460:Crystallization; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D011487:Protein Conformation; D053838:Scattering, Small Angle
chemical_list: D001221:Aspartate Carbamoyltransferase