1986 Volume 34 Issue 3 Pages 1219-1222
A thymidine phosphorylase (TP) preparation was partially purified from human gastric cancer (poorly differentiated adenocarcinoma). The specific activity of the final preparation represented a 379-fold purification of the 7000g supernatant of tissue homogenate. The phosphorolytic activities toward thymidine (dThd), 5'-deoxy-5-fluorouridine (5'-DFUR), and 1-(tetrahydro-2-furanyl)-5-fluorouracil (Tegafur) remained closely in parallel during the whole purification procedure. The results provide evidence in support of the assumption that 5'-DFUR and Tegafur are converted into 5-fluorouracil, an activated form of the antitumor agents, in humn tumor tissues by a TP activity. The values of Km of the TP preparation were 1.68×10-4, 1.72×10-3, 1.33×10-2, and 4.76×10-2M for dThd, 5'-DFUR, Tegafur, and uridine, respectively.