Two forms of thymidine kinase in normal and tumor tissues of animals.

The thymidine kinases extracted from the spleen of mice infected with Friend virus and from Yoshida sarcoma in rats were separated into two active peaks by diethylaminoethyl cellulose column chromatography, while those of normal tissues have been found to consist of only the first peak (P-1). The second peak (P-II) was also found in the enzyme from the extract of the spleen when the animals were treated by i.p. injections of 1-acetyl 2-phenylhydrazine. The two P-II peaks from tumor tissue and from spleen enlarged by anemia-inducing agents were indistinguishable on the chromatographic profile. On the other hand, the thymidine kinase extracted with Triton X-100 from a mitochondrial fraction of normal liver was found to consist of only one peak in the same position as the above P-II's on the chromatogram, but its faculty for deoxythymidine triphosphate inhibition was not identical to that of tumor tissue. This treatment with the detergent might cause dissociation of a certain component from the enzyme complex to make the extra peak (P-IIb), but it eventually shifts to P-II on the chromatogram.