[Structural peculiarities of the nucleic factor from ascitic fluid of tumors].

Several characteristics of the nucleic factor of tumors which is thought to play an important role in suppression of tumor immunity was investigated. This nucleic factor differs from native double-stranded DNA of eukaryotic nuclei by base composition (A: T: G : C = 1: 1.44 : 0.91: 0.69); its affinity to GAP and hyperchromic effect were lower than those in native DNA. Heating above 80 degrees in 1 N KOH destroyed the nucleic factor to fragments that could not be detected in 8% PAK electrophoresis. The results of this and previous reports lead us to a hypothesis that the nucleic factor is a DNA molecule consisting of single- and double-stranded regions, as well as short insertions of RNA. The double-stranded regions in this molecule possess non-parrallel breaks.