[Structural changes in chromatin during activation of transcription coupled with translation inhibition by...

A chromatin preparation isolated one hour after cycloheximide injection possesses a higher RNA-synthesizing activity and is split by DNAase I to a greater extent as compared to chromatin of control hepatocytes. Thermal denaturation of this preparation causes a considerable increase (about 2-fold) in the content of the thermolabile fraction melting in the free DNA denaturation zone. The relative content of fast repetitions in the thermolabile fraction (1 hour after the beginning of experiment) is lower than that in control. The type of changes in the viscosity of chromatin in the predenaturation zone isolated one hour later suggests a more labile binding of DNA to the protein. Chromatin preparation isolated 3 hours after cycloheximide injection is characterized by intermediate values of all parameters under study, as compared to the two other preparations used in this experiment. It is assumed that the activation of transcription coupled with the inhibition of translation by cycloheximide is determined by the appearance of elongated segments of free or weakly bound DNA in the chromatin preparation.