The conversion of citrulline to arginine (transimination) by tissue slices and homogenates.

The conversion of citrullme to arginine by a transimination reaction involving glutamic acid and metabolically related compounds has been reported to take place in kidney slices by Borsook and Dubnoff (1). These authors found that liver slices did not catalyze the reaction and further that the breakdown of cell structure of kidney tissue, such as by homogenization, resulted in a loss of activity. In the course of an investigation on the mechanism of urea synthesis in liver, some evidence for the transimination reaction was obtained in homogenates fortified with adenosine triphosphate (ATP), magnesium ions, and cytochrome c. These findings, which are reported in a separate publication (2), led to a study of the transimination reaction in kidney and other tissue homogenates. Experiments reported in this paper deal with (1) the conditions l;equired for demonstrating the transimination reaction in tissue homogenates and (2) the relative rates of this reaction in slices ati homogenates of kidney and liver.