title: Circular dichroism studies of the interaction of a limited hydrolysate of T4 gene 32 protein with T4 DNA and poly[d(A-T)].poly[d(A-T)].
abstract: gp32 I is a protein with a molecular weight of 27 000. It is obtained by limited hydrolysis of T4 gene 32 coded protein, which is one of the DNA melting proteins. gp32 I itself appears to be also a melting protein. It denatures poly[d(A-T)].poly[d(A-T)] and T4 DNA at temperatures far (50-60 degrees C) below their regular melting temperatures. Under similar conditions gp32 I will denature poly[d(A-T).poly[d(A-T)] at temperatures approximately 12 degrees C lower than those measured for the intact gp32 denaturation. For T4 DNA gp32 shows no melting behavior while gp32 I shows considerable denaturation (i.e., hyperchromicity) even at 1 degree C. In this paper the denaturation of poly[d(A-T)].poly[d(A-T)] and T4 DNA by gp32 I is studied by means of circular dichroism. It appears that gp32 I forms a complex with poly[d(A-T)]. The conformation of the polynucleotide in the complex is equal to that of one strand of the double-stranded polymer in 6 M LiCl. In the gp32 I DNA complex formed upon denaturation of T4 DNA, the single-stranded DNA molecule has the same conformation as one strand of the double-strand T4 DNA molecule in the C-DNA conformation.
mesh_terms: D002942:Circular Dichroism; D004265:DNA Helicases / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D005814:Genes, Viral; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D010446:Peptide Fragments / Q000378:metabolism; D011067:Poly dA-dT / Q000378:metabolism*; D011089:Polydeoxyribonucleotides / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D004277:DNA, Single-Stranded; D004279:DNA, Viral; D010446:Peptide Fragments; D011089:Polydeoxyribonucleotides; D014764:Viral Proteins; D011067:Poly dA-dT; D004265:DNA Helicases