ACTIVATION OF DEOXYRIBONUCLEOPROTEIN IN HUMAN LEUCOCYTES STIMULATED BY PHYTOHEMAGGLUTININ .2. STRUCTURAL CHANGES OF DEXOYRIBONUCLEOPROTEIN AND SYNTHESIS OF RNA

The increase in acridine orange (AO) binding sites in the DNP complex occurring in human leucocytes during the first 60 min after PHA stimulation was found to be paralleled by a decreased heat stability as well as a more regular arrangement and stretching of the DNP complex. These findings support the theory that the binding between DNA and surrounding proteins in the DNP complex is altered by the action of PHA and that thereby increasing numbers of DNA phosphate groups become uncovered. Increasing amounts of low ordered ribonucleic acids were found in mononuclear leucocytes if more than half of all AO binding sites became accessible to AO. Above this value a correlation was found between the number of AO binding sites in DNP uncovered during the initial phase of PHA stimulation, and the amount of low ordered RNA found 1 and 48 h after PHA administration. The data suggest that this activation of the DNP complex acts as one necessary trigger for RNA synthesis and that the role of basic proteins in gene regulation might be confined to this trigger process preceding a more specific and refined mechanism for gene regulation. © 1969.