The biological effect of a nonprotein component removed from neocarzinostatin (NCS).

The biological effects of both nonprotein component (NPC) and PC (protein component) from NCS have been studied in vivo and in vitro. NPC was found to not only inhibit DNA synthesis in growing cells but also induce DNA degradation in vivo and in vitro. However, neither these two biological activities of PC were detected even at a 100-times higher concentration of NPC (0.2 micrograms/ml) which inhibited 50% DNA synthesis in growing cells. NPC-induced DNA degradation in vitro was stimulated by 2-mercaptoethanol as has been reported for NCS. These results show that the NPC removed from NCS is responsible for the biological activities such as the inhibition of DNA synthesis in growing cells and the induction of DNA degradation in vivo and in vitro.