Interaction of two LAC repressor protein segments with polynucleotides

Rao, M. V. R. ; Atreyi, M. ; Suresh Kumar, G. ; Kumar, Satish ; Chauhan, V. S. (1985) Interaction of two LAC repressor protein segments with polynucleotides Journal of Biosciences, 8 (3-4). pp. 635-644. ISSN 0250-5991

PDF - Publisher Version

Official URL:

Related URL:


The interaction of the oligopeptides Ala-Gln-GIn-Leu-Ala-Gly-OH and Gln-Leu- Ala-Gly-OMe corresponding, respectively, to the sequence 53-58 and 55-58 of lac repressor protein with four polynucleotides was studied. The two peptides did not interact with poly dA. poly dT, poly d(A-T).poly d(A-T) or poly d(A-G).poly d(C-T). But they interacted in a characteristic way with poly d(A-C). poly d (G-T), the sequences of which are in abundance in the lac operator region. Both the peptides stabilised the melting of poly d (A-C). poly d (G-T) at a peptide to nucleotide ratio (P/N) of 4; at lower ratios, they destabilised the DNA slightly. The circular dichroism of the alternating polynucleotide with CAC/GTG sequences was perturbed by both the oligopeptides. The hexapeptide at a P/N of 4 caused the transformation of the B form circular dichroism spectrum to a new state, characterised by strong 220 and 240 nm bands, and a rather weak long wavelength spectrum.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Lac Repressor Protein; Hexapeptide; Poly d(A-C). Poly d(G-T); Circular Dichroism Spectra; Protein-nucleic Acid Interactions
ID Code:77500
Deposited On:12 Jan 2012 14:36
Last Modified:18 May 2016 20:44

Repository Staff Only: item control page