Explain Carbamoyl Phosphate Synthetase (CPSI) ?

In the first step, the mitochondria1 enzyme Carbamoyl Phosphate Synthetase 1 converts the ammonia produced by glutamate dehydrogenase into carbarnoyl phosphate.

See Figure which illustrates the entire urea cycle. The formation of carbamoyl phosphate requires 2 molecules of ATP and takes place in the matrix of mitochondria. The ammonium may come from glutamate (as learnt earlier by the action of L-glutamate dehydrogenase) or in free form (as NH,) from blood. Pi is inorganic phosphate. ATP, as usual, functions as a magnesium-ATP complex. Carbamoyl phosphate is further transferred to ornithine. Let us learn about this in the next step.