The utilization and formation of dicarboxylic amino acids by cell suspensions of normal and malignant lymphatic tissues.

The free amino acid pattern of rodent lymphosarcomas was found to differ in a number of re spects from that of normal lymphatic tissues (6). One of the differences pertains to aspartate, the concentration of which was relatively low in the tumors, despite the fact that there was consider able oxalacetic-glutamic transaminase activity in these tissues. Moreover, when cell suspensions of the Gardner lymphosarcoma or mouse spleen cells were incubated with lactate-2-C14, the ratios of total radioactivity in free aspartate :glutamate : alanine were as follows: 0.2:1.0:2.0 in tumor and 0.9:1.0:0.6 in spleen cells (8). These results sug gested that an abnormality existed in the metabo lism of the tumor cells whereby either little aspar tate was formed in these cells or the utilization of this amino acid was unusually rapid. A study was therefore made of the metabolism of aspartate, with C'Mabeled compounds. Cell suspensions of rabbit appendix, rat thymus, mouse spleen, and two mouse lymphosarcomas were incubated with acetate-2-C14, DL-glutamate2-C14, succinate-2-C14, and DL-aspartate-4-C14.