Analysis of the control of citrulline synthesis in isolated rat‐liver mitochondria

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Abstract
The amount of control of the various steps involved in the citrulline synthesizing pathway in isolated rat-liver mitochondria incubated with saturating concentrations of ammonia and ornithine has been measured. 1 The flux control coefficient of carbamoyl-phosphate synthase (ammonia) was close to one. Control exerted by other steps in the pathway, including ornithine transcarbamoylase, carbonic anhydrase, ATP production and transport of ornithine, was negligible. 2 The high flux control coefficient of carbamoyl-phosphate synthetase is due to the low elasticity coefficient of this enzyme towards its product, intramitochondrial carbamoyl phosphate, in combination with a high elasticity coefficient of ornithine transcarbamoylase towards carbamoyl phosphate.