title: Binding of lac repressor headpiece to poly[d(A-T)]. A thermal denaturation study.
abstract: The binding of the lac repressor headpiece to poly[d(A-T)] has been investigated using thermal denaturation experiments. The binding of the headpiece leads to a stabilization of the double-stranded structure. Competition experiments using circular dichroism measurements confirm that the headpiece binds stronger on the double-stranded poly[d(A-T)] than on a single-stranded nucleic acid like poly(A). Theoretical analyses of the melting curves allow the determination of the binding constant and of the site size on the poly[d(A-T)]. This latter value is found to be 4 base pairs, in good agreement with that determined by other experimental approaches, and is much smaller than the values previously found for the lac repressor.
mesh_terms: D002942:Circular Dichroism; D004926:Escherichia coli / Q000235:genetics; D006358:Hot Temperature; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D011067:Poly dA-dT / Q000378:metabolism*; D011089:Polydeoxyribonucleotides / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D011089:Polydeoxyribonucleotides; D012097:Repressor Proteins; D014157:Transcription Factors; D011067:Poly dA-dT