A Study of d-Amino Acid Oxidase, Uricase, and Choline Oxidase in the Livers and in Isolated Liver Cell Nuclei of Rats Bearing Transplanted Tumors*

Since the report of Brahn (1) that very low catalase values are found in the livers of human beings dead of various forms of cancer, many papers have appeared on the effect of a growing tumor upon enzyme systems in liver tissue. Greenstein (4) has shown that in rats bearing transplanted hepatoma 31 or Jensen sarcoma, or in mice bearing various transplanted tumors, the activity of the liver catalase is notably decreased, but the activity of xanthine dehydrogenase and of acid and alkaline phosphatase is normal. Greenstein also has shown that arginase is decreased in the livers of tumorbearing rats but not in the livers of tumor-bearing mice. Shack (8) has reported that the d-amino acid oxidase is not significantly low in the livers of rats bearing transplanted hepatoma 31, although the concentration of riboflavin has been found low in the livers of rats bearing transplanted tumors. However, no attempt has been made to determine the apoenzyme and coenzyme of d-amino acid oxidase separately. In this Work we have investigated apoenzyme and coenzyme of d-amino acid oxidase separately and have found that the presence of subcutaneous transplants of hepatoma 31 causes significant lowering of both d-amino acid oxidase apoenzyme and coenzyme in whole liver tissue of nits bearing this tumor and in nuclei isolated from the liver cells. We have also investigated the enzymes uricase and choline oxidase in the livers of rats bearing transplanted tumors and in nuclei isolated from the cells of these livers. No work on the latter two enzymes has previously been reported in this connection.