[Investigations upon the binding of plant growth substances to several components of the chromatin in vitro : II. experiments with differently reconstituted nucleoproteins].

Several growth substances (IAA, α-NAA) are able to reduce thermal stability of artificially reconstituted nucleoproteins without splitting off measurable amounts of protein from DNA. This effect is not shown by substances structurally related to auxins (β-NAA, tryptophan), but other growth substances (GA, KI) also reduce thermal stability of several reconstituated nucleoproteins.The effect of growth substances on the Tm of nucleoproteins strongly depends upon the concentration of the growth substances. The effective concentrations of IAA are lowered by increasing acidity of the protein component in the nucleoprotein. IAA and GA diminish the binding capacity of histones and residual nucleoproteins to DNA at different concentrations.Nucleoproteins containing histones and residual nuclear proteins (DNA/resid. prot. 1:0,5: 0,5) exhibited different thermal stability depending on whether part of the histones or residual nuclear proteins were first bound to DNA. Furthermore, these nucleoproteins showed different thermal stability after treatment with growth substances.