Biopolymers and cell. 1989. Volume 5. № 4. 90 - 97

D. Yu. Blokhin, V. A. Struchkov

A PROBLEM ON THE SUPRAMOLECULAR ORGANIZATION OF EUKARYOTIC NUCLEOIDS

Summary

    Properties of the nucleoids isolated from murine leukemia L1210 cells were studied using capillary viscoelastometry and sedimentation methods. Thiols (2-mercaptoethanol, dithiothreitol), pronase P, RNAse A, ethanol, sodium trichloracetate, as well as heating to 60 °C and 95 °C have been studied for their effects on nucleoids. Nucleoid cage damage by thiols or pronase has been shown to cause decompactization of the complex without loss of superhelical conformation by DNA domains. Decompactization of the complex structure is also observed when isolated nucleoids are exposed to RNAse A in the medium with low ionic strength; no decompactizing effect of RNAse A on the nucleoid structure has been revealed in other variants of enzyme treatments. Heating of the nucleoid preparations up to the «melting temperature* of the DNA double helix is shown to induce total relaxation of superhelical domains and degradation of the complex.