title: DNA unwinding component of the nonhistone chromatin proteins.
abstract: A subclass of nonhistone chromatin proteins from rat liver, previously shown to exhibit high affinity for DNA, has been fractionated by single-stranded DNA-agarose affinity chromatography. The protein fraction that bound to DNA-agarose in 0.19 M NaCl-buffer and was eluted with 2 M NaCl-buffer is enriched for a protein component of approximately 20,000 daltons and exhibits preferential binding to denatured DNA. This nonhistone protein fraction specific for single strands binds to DNA in a non-species-specific manner, and causes helix-coil transition of synthetic poly[d(A-T)-d(A-T)] at 25 degrees, as indicated by the increase in absorbance of ultraviolet light at 260 nm. The observed hyperchromicity does not result from any nuclease activity in the protein fraction, because addition of Mg+2 results in partial hypochromic shift, and the protein/DNA complex is retained by nitrocellulose filters.
mesh_terms: D000818:Animals; D001665:Binding Sites; D002868:Chromosomal Proteins, Non-Histone / Q000302:isolation & purification / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism; D009690:Nucleic Acid Conformation; D011067:Poly dA-dT / Q000378:metabolism; D011485:Protein Binding; D051381:Rats
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D011067:Poly dA-dT; D004247:DNA