Apparent cooperativity for carbamoylphosphate in Escherichia coli aspartate transcarbamoylase only reflects cooperativity for aspartate
نویسندگان
چکیده
منابع مشابه
Thermodynamics of assembly of Escherichia coli aspartate transcarbamoylase.
Reaction microcalorimetry and potentiometry have been used to define the thermodynamics of assembly of Escherichia coli aspartate transcarbamoylase (aspartate carbamoyltransferase, carbamoylphosphate:L-aspartate carbamoyltransferase, EC 2.1.3.2) from its catalytic and regulatory subunits and the linkage between assembly and proton binding. Over the pH range 7-9.5 and the temperature range 15-30...
متن کاملAssembly of catalytic subunits of aspartate transcarbamoylase from Escherichia coli.
participate in different ways in the assembly of the complex. The positioning of a subunit in the complex may be crucial to its function. The dynamic equilibrium between various assembly states of a heteropolymer cannot be treated as if the assembly involves structurally homogeneous elements whose association reactions can be described by a single interaction constant. On the contrary, each sta...
متن کاملEffectors of Escherichia coli aspartate transcarbamoylase differentially perturb aspartate binding rather than the T-R transition.
New systematic methods developed for equilibrium isotope exchange kinetics have been used to analyze the effects of activator ATP and inhibitor CTP with Escherichia coli aspartate transcarbamoylase. This indepth approach requires (a) variation of [modifier] with fixed subsaturating levels of substrates, and (b) variation of at least three combinations of reactant-product pairs in constant ratio...
متن کاملA kinetic model of cooperativity in aspartate transcarbamylase.
A relatively simple kinetic model is proposed to account simultaneously for data on the binding of carbamyl phosphate and succinate to aspartate trans carbamylase (ATCase), and for the relaxation spectrum associated with this binding. The model also accounts for measurements of the initial velocity of the reaction of ATCase with respect to aspartate and carbamyl phosphate. The principal assumpt...
متن کاملImportance of domain closure for the catalysis and regulation of Escherichia coli aspartate transcarbamoylase.
Two hybrid versions of Escherichia coli aspartate transcarbamoylase were studied to determine the influence of domain closure on the homotropic and heterotropic properties of the enzyme. Each hybrid holoenzyme had one wild-type and one inactive catalytic subunit. In the first case the inactive catalytic subunit had Arg-54 replaced by alanine. The holoenzyme with this mutation in all six catalyt...
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ژورنال
عنوان ژورنال: European Journal of Biochemistry
سال: 1994
ISSN: 0014-2956,1432-1033
DOI: 10.1111/j.1432-1033.1994.tb18924.x