Presence of D-aspartate and D-glutamate in tumor proteins.

Over 50 years ago Kogl and Erxleben reported that tumor proteins contain appreciable amounts of D-amino acids. This postulate remained highly controversial for several years, during which time several researchers either supported or refuted the hypothesis. We have analyzed several sets of tumors and normal control tissues for the presence of D-aspartate (D-Asp) and D-glutamate (D-Glu). Most tumors contain less D-Asp than the control tissues, whereas nearly half of the tumors contain 1.6 to 5.4 times more D-Glu than the controls. The tumors averaged 0.72% D-Asp and 0.61% D-Glu compared to 0.94% D-Asp and 0.35% D-Glu in the control tissues. However, within the limits of experimental error, there is no significant difference in the level of these D-amino acids between the tumors and normal tissues.