What compound(s) were the most effective inhibitors and what compound(s) were the most effective activators? Aspartate transcarbamoylase (ATCase) catalyzes an early step in the synthesis of thepyrimidine nucleotides UTP and CTP. The enzyme catalyzes the condensation of carbamoylphosphate and aspartate to form carbamoyl aspartate. The reaction pathway is shown inFigure 16.1 below. The enzyme has been fairly well characterized. It is known to consist ofsix regulatory subunits and six catalytic subunits.HCO3 + Glutamine + ATPCarbamoyl phosphate + AspartateATCaseFigure 16.1: Pyrimidine synthetic pathway.N-carbamoylaspartateUMPUTPCTPIn this case, we examine the properties of ATCase isolated from E. coli to illustrate some ofthe important regulatory properties of multi-subunit enzymes. As an early enzyme in a multi-step pathway, the ATCase reaction is a logical one to regulate the synthesis of pyrimidinenucleotides. Both purine nucleotides and pyrimidine nucleotides are needed in roughly equalamounts as substrates for DNA synthesis in rapidly dividing cells. The regulation of theATCase enzyme ensures a proper balance of purine and pyrimidine pools in E. coli. The goalin this case was to identify the cellular metabolites that serve as activators and inhibitors ofATCase.

ATCase is more commonly known as Aspartate carbamoyltransferase or aspartate transcarbamoylase.…

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Biochemistry

What compound(s) were the most effective inhibitors and what compound(s) were the most effective activators?

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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