What regulates aspartate Transcarbamoylase?
Table of Contents
Aspartate transcarbamoylase (ATCase) is a key enzyme which regulates and catalyzes the second step of de novo pyrimidine synthesis in all organisms. Escherichia coli ATCase is a prototypic enzyme regulated by both product feedback and substrate cooperativity, whereas human ATCase is a potential anticancer target.
How is aspartate Transcarbomylase regulated?
ATCase is allosterically regulated by NTPs binding to the interface between adjacent regulatory subunits. Each allosteric site contains two nucleotide-specific subsites, A and B, that each bind one NTP and are bridged by a Mg2+ cation (or another divalent cation like Zn2+ or Ca2+).
Which of the following is the activator of enzyme ATCase?
Adenosine triphosphate (ATP) is an allosteric activator, and together CTP and ATP act on ATCase to coordinate the rates of purine and pyrimidine nucleotide biosynthesis.
Is aspartate Transcarbamoylase a transferase?
Aspartate carbamoyltransferase (also known as aspartate transcarbamoylase or ATCase) catalyzes the first step in the pyrimidine biosynthetic pathway (EC 2.1. 3.2). In E. coli, the enzyme is a multi-subunit protein complex composed of 12 subunits (300 kDa in total).
What is the role of aspartate Transcarbamoylase?
Aspartate transcarbamoylase (ATCase) catalyzes the committed step, the condensation of carbamoyl phosphate and aspartate to form carbamoyl aspartate and inorganic phosphate, in pyrimidine nucleotide biosynthesis for E. coli.
What is the function of aspartate Transcarbamoylase?
What is allosteric enzyme regulation?
Allosteric regulation occurs when an activator or inhibitor molecule binds at a specific regulatory site on the enzyme and induces conformational or electrostatic changes that either enhance or reduce enzyme activity. Not all enzymes possess sites for allosteric binding; those that do are called allosteric enzymes.
What are catalytic strategies?
Enzymes are proteins that catalyze a reaction by stabilizing the transition state and therefore, lowering the activation energy of the reaction. To achieve this, enzymes use different classes of reactions known as catalytic strategies.
What are the different types of enzyme regulation?
Allosteric regulation, genetic and covalent modification, and enzyme inhibition are all types of enzymatic regulation. Enzymes can be inhibited in three ways: competitive inhibition, non-competitive inhibition, or uncompetitive inhibition.
What is aspartate transcarbamoylase (ATCase)?
Aspartate Transcarbamoylase (ATCase) is an allosterically regulated enzyme with unique quaternary structure involving separable catalytic and regulatory subunits. This allosteric regulation affects the kinetics of the enzyme. ATCase consists of two catalytic trimers and three regulatory dimers that are completely separable units.
Why are the aspartate and carbamoyl phosphate domains brought closer together?
Furthermore, the aspartate and carbamoyl phosphate domains of each catalytic sub-unit are brought closer together because of the interaction between glutamate-50 and both arginine-167 and arginine-234, and between serine-171 and both glutamine-133 and histidine-134, helping to create an active site pocket.
How does transcarbamoylase make pyrimidines?
Aspartate Transcarbamoylase catalyzes the first step in the biosynthesis of pyrimidines ( specifically called N-carbamoyl-aspartate) which ultimately yield pyrimidine nucleotides such as CTP (Cytidine Triphosphate). The cell must precisely regulate the amount of CTP in the cell because making it can be energetically expensive.
What are the inhibitors and activators of carbamoyl phosphate synthase?
The carbamoyl phosphate synthase is controlled allosterically by both the inhibitor UMP and the activator IMP, and in agreement with carbamoyl phosphate being part of the arginine biosynthesis, the activator ornithine.