OTC and psoriasis: Glutamate which level is significantly higher in psoriasis patients samples (p = 0.002) can be converted by glutamine synthetase (EC 6.3.1.2) to glutamine which is subsequently converted by carbamoyl-phosphate synthetase (EC 6.3.4.16) to carbamoyl-P which is then converted by ornithine carbamoyltransferase (EC 2.1.3.3) to citrulline that is an essential component of the urea cycle [23].