Evidence for the presence in calf thymus of a peptidic factor controlling DNA transcription in vitro.
A thymic factor causes a strong inhibition of the DNA-directed RNA polymerase reaction in vitro. The active factor was isolated from aqueous ultrafiltered thymus extracts and purified by means of chromatography on DEAE-cellulose and then on Dowex 50 WX2. The purified thymic factor was characterized as a peptide of low molecular weight (less than 5000). The biological activity of the thymic factor cannot be attributed to the presence of a nuclease or of a histone fragment. The RNA synthesis is controlled by this factor by means of electrostatic interactions between the peptide compound and DNA. Inhibitory activity on RNA synthesis was absent from kidney extracts.
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009691:Nucleic Acid Denaturation; D010455:Peptides / Q000302:isolation & purification / Q000378:metabolism*; D011370:Proflavine; D013696:Temperature; D013950:Thymus Gland / Q000378:metabolism*; D014158:Transcription, Genetic
D010455:Peptides; D004247:DNA; D011370:Proflavine; D012321:DNA-Directed RNA Polymerases