Biochemistry: The Chemical Reactions of Living Cells, Volume 2 - D. Metzler 1980

Enzymes: Protein Catalysts of the Cell
Enzyme Inhibition and Activation
Regulatory Subunits

There are known Enzymes (and their number is steadily growing) which, along with “catalytic” subunits bearing active sites, contain regulatory subunits that interact weakly (or, conversely, strongly) with the catalytic subunits and act as allosteric modifiers. In turn, regulatory subunits can undergo Conformational changes induced by the binding of inhibitors or activators. The best example of this is aspartate carbamoyltransferase (Chap. 4, Sec. D). Its regulatory subunits contain binding sites for cytidine triphosphate (CTP), which acts as a specific enzyme inhibitor. The Significance of this inhibition from a regulatory standpoint becomes apparent when considering that aspartate carbamoyltransferase catalyzes the first reaction in the Pyrimidine Nucleotide Biosynthesis pathway (Chap. 14, Sec. L, 1). CTP is the end product of this pathway and causes feedback inhibition of the enzyme.



Last update: 06/08/2026

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