Wheat-germ aspartate transcarbamoylase. Kinetic behaviour suggesting an allosteric mechanism of regulation
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چکیده
منابع مشابه
Dissecting enzyme regulation by multiple allosteric effectors: nucleotide regulation of aspartate transcarbamoylase.
The enzyme aspartate transcarbamoylase (ATCase, EC 2.1.3.2 of Escherichia coli), which catalyzes the committed step of pyrimidine biosynthesis, is allosterically regulated by all four ribonucleoside triphosphates (NTPs) in a nonlinear manner. Here, we dissect this regulation using the recently developed approach of random sampling-high-dimensional model representation (RS-HDMR). ATCase activity...
متن کاملActive-site-directed inactivation of wheat-germ aspartate transcarbamoylase by pyridoxal 5'-phosphate.
Treatment of 1 microM wheat-germ aspartate transcarbamoylase with 1 mM-pyridoxal 5'-phosphate caused a rapid loss of activity, concomitant with the formation of a Schiff base. Complete loss of activity occurred within 10 min when the Schiff base was reduced with a 100-fold excess of NaBH4. Concomitantly, one amino group per chain was modified. No further residues were modified in the ensuing 30...
متن کاملAllosteric regulation of catalytic activity: Escherichia coli aspartate transcarbamoylase versus yeast chorismate mutase.
Allosteric regulation of key metabolic enzymes is a fascinating field to study the structure-function relationship of induced conformational changes of proteins. In this review we compare the principles of allosteric transitions of the complex classical model aspartate transcarbamoylase (ATCase) from Escherichia coli, consisting of 12 polypeptides, and the less complicated chorismate mutase der...
متن کاملIn the presence of CTP, UTP becomes an allosteric inhibitor of aspartate transcarbamoylase.
The allosteric control of aspartate transcarbamoylase (ATCase, EC 2.1.3.2) of Escherichia coli involves feedback inhibition by both CTP and UTP rather than just CTP alone. It has been known that CTP functions as a heterotropic inhibitor of catalysis; however, the inhibition by CTP alone is incomplete (50-70% at various aspartate concentrations) and there is only a partial occupancy of the allos...
متن کاملTrapping and structure determination of an intermediate in the allosteric transition of aspartate transcarbamoylase.
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 t...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1972
ISSN: 0306-3283
DOI: 10.1042/bj1280311