Labeling reactions of l-lysine and poly-l-lysine with 57Co and their distribution in normal and ehrlich ascites tumor-bearing mice

The labeling reactions of L-lysine and poly-L-lysine (average of molecular weight: 3400 (I), 15000 (II), 25000 (III) and 87000 (IV)) with 57Co2+ ions and the tumor and organ distributions of their complexes were examined. L-Lysine and poly-L-lysine with 57Co2+ ions were incubated for 20 hrs at 300C in the solution of pH 9.0 and 50 v/v% ethanol solution of pH 10.5, respectively. L-Lysine and poly-L-lysine were labeled with 57Co2+ ions in the radiochemical yields of over 95 and 60 - 70%, respectively. The radioactive polypeptides were separated from unreacted 57Co2+ ions in the range of pH 8.0 to 8.5 by means of gel filtration on Sephadex G-25 M column (1.5 x 5.0 cm). The radioactive complexes were injected intravenously in mice. L-Lysine complex was excreted rapidly from tumor tissue and various organs. The localization of poly-L-lysine complexes in tumor was higher 3 to 5 times than that of L-lysine complex at 20 hrs after injection. The localization in tumor increased in the order of L-lysine-<II-<I-complex. II-Complex was excreted scarcely from tumor. 57Co-poly-L-lysine complexes revealed remarkably high localization in liver and spleen. The localization in tumor of those complexes seemed to be related to the molecular weight and the positive charge of lysine. (author)