Zum Wirkungsmechanismus von Induktionsstoffen, I. Fraktionierung von Kalbsthymus-Chromatin und Charakterisierung eines spezifischen DNA-Protein-Komplexes

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Abstract
The solubility of calf thymus chromatin in relation to the ionic concentration is described. If the chromatin particles are washed with Versene-buffer at pH 8.0 the associated acidic proteins are dissolved. When the chromatin is fractionated by hydrochloric acid a residual complex remains, which consists of DNA, RNA, and 30-40% basic proteins. Unlike the histones these proteins are soluble in acids only in the presence of urea. Their isolation is possible if the DNA is degraded by enzymes. The binding of these proteins to DNA is remarkable. Separation is not achieved by high salt concentrations, 8[image] urea, cation- and anion exchange methods or by density gradient centrifugation. After enzymatic digestion of the DNA by DNase and venom phosphodiesterase fragments result which contain these proteins, but are acidic due to the presence of associated nucleotides. These fragments cannot be dissociated by SE-Sephadex or by ultracentrifugation. Treatment with alkali at 0[degree]C allows a further separation of the residual complex by ion exchange columns and ultracentrifugation. The residual complex has priming activity in DNA dependent RNA synthesis and contains double stranded DNA.

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