Purification and Properties of Ornithine Carbamoyl Transferase 1 from Alnus glutinosa Root Nodules

Summary The main isoform of ornithine carbamoyl transferase (carbamoyl phosphate: L-ornithine carbamoyl transferase; EC 2.1.3.3) from Alnus glutinosa root nodules, called OCT 1 , has been purified to electrophoretic homogeneity. The homogeneous enzyme has a specific activity of 93 nkat per milligram of protein. The molecular mass of the native protein as determined from polyacrylamide gradient gel electrophoresis is 200,000±10,000. The ornithine carbamoyl transferase 1 has a K m value for ornithine of 10.0 mM and displays apparent inhibition with respect to ornithine. K m values for carbamoyl phosphate are found in the range 1.1 to 2.8 mM depending of the ornithine concentration.