Question

Aspartate transcarbamoylase (ATCase) is a typical enzyme that is regulated to regulate the enzyme's entire pathway in that

A. it catalyzes a very energetically favorable reaction,
B. it catalyzes a step that commits metabolites to a pathway,
C. it is allosterically regulated,
D. it is multimeric - has multiples subunits
E. All of the above

Answer 1

Aspartate transcarbamoylase (ATCase) regulates pyrimidine biosynthesis and exhibits allosteric regulation, commits substrates to the pathway, and is a multimeric enzyme. It is also controlled by feedback inhibition.

Step-by-step explanation:

Aspartate transcarbamoylase (ATCase) is an enzyme that plays a pivotal role in the regulation of the pyrimidine biosynthesis pathway. It embodies several regulatory characteristics that are essential for controlling the flow of metabolites through the pathway, including its role in the committed step of the process.

ATCase is subject to allosteric regulation, changing its activity in response to the concentrations of certain effector molecules. This enzyme is also multimeric, with multiple subunits contributing to its functional and regulatory properties. Specifically, ATCase catalyzes a step that commits substrates to continuing down the pyrimidine biosynthesis pathway, thereby making it a strategic point of regulation. The feedback inhibition by the end product, CTP, makes it an excellent example of how metabolic enzyme activity is precisely controlled in the cell.