Carbamoyl phosphate synthetase catalyzes the conversion of bicarbonate, ATP, and NH4 into carbamoylphosphate. This reaction is the first step in the urea cycle. This protocol measures activity by coupling the CPS reaction to the ornithine transcarbamylase reaction to produce citrulline. Citrulline is then measured using a colorimetric technique, the Ceriotti method. Specimen Requirements:The assay is only performed on liver. Send > 10 mg of tissue. The tissue must be frozen rapidly after collection. Do not add any liquid to the sample. Ship on dry ice in an insulated contained by overnight carrier. Normal Range:Liver: 100-250 µmol/hr/gm tissue Turnaround Time:3 weeks CPT Codes and Prices:82657, 84155, 84311, 84520 Shipping InformationForms:Test Codes:4561 |