In de novo pyrimidine biosynthesis (biochemistry), the pyrimidine ring is constructed first and later attached to the pentose sugar, with aspartate transcarbamoylase (ATCase) catalyzing the committed second reaction (carbamoyl phosphate + aspartate → carbamoyl aspartate) en route to UMP and ultimately CTP. ATCase is regulated allosterically: CTP, the pathway's end product, inhibits ATCase via feedback inhibition, while ATP activates it, together balancing the total amount of pyrimidines produced and the relative ratio of purines to pyrimidines needed for correct nucleic acid base pairing; aspartate itself also activates ATCase as a signal of amino acid sufficiency for proceeding with nucleotide synthesis.
In de novo pyrimidine biosynthesis (biochemistry), the pyrimidine ring is constructed first and later attached to the pentose sugar, with aspartate transcarbamoylase (ATCase) catalyzing the committed…