The d-Amino Acid Oxidase, Uricase, and Choline Oxidase in Two Transplanted Rat Tumors and in Isolated Nuclei of Tumor Cells*

In order to determine whether or not changes in enzymatic activity specifically accompany neoplasia, and to what extent such changes may occur, many enzymes have been investigated by Greenstein (2) in both normal and neoplastic tissues. Shack (3) has reported that d-amino acid oxidase is low in rat hepatoma 31, and suggested that the lowering of the enzyme may be owing to a deficiency in protein component as well as in the flavin prosthetic group of the enzyme, but no attempt has been made to determine the apoenzyme and coenzyme of d-amino acid oxidase separately. Furthermore, very little work has been done on the change in distribution of enzymes between the nuclei and cytoplasm of tumor tissue, owing to lack of availability of satisfactory preparations of tumor cell nuclei. In this work both the apoenzyme and coenzyme of d-amino acid oxidase have been studied in whole tumor tissue and in isolated nuclei of tumor cells. A study has been made, also, of the enzymes uricase and choline oxidase, two enzymes hitherto not investigated in tumor tissue.