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Binding of lac repressor headpiece to poly[d(A-T)]. A thermal denaturation study
Biochemical and Biophysical Research Communications
|January 14, 1983
Summary
The lac repressor headpiece stabilizes double-stranded DNA. It binds more strongly to double-stranded poly[d(A-T)] than single-stranded nucleic acids, with a site size of 4 base pairs.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- The lac repressor controls gene expression by binding to DNA.
- Understanding repressor-DNA interactions is crucial for molecular biology.
- The specific binding affinity and site size of the lac repressor headpiece are key parameters.
Purpose of the Study:
- To investigate the binding of the lac repressor headpiece to poly[d(A-T)].
- To determine the binding constant and site size of this interaction.
- To compare binding to double-stranded versus single-stranded nucleic acids.
Main Methods:
- Thermal denaturation experiments were used to study DNA stabilization.
- Circular dichroism measurements were employed for competition binding assays.
- Theoretical analysis of melting curves provided quantitative binding data.
Main Results:
- The lac repressor headpiece binding stabilizes the double-stranded poly[d(A-T)] structure.
- Competition experiments showed stronger binding to double-stranded DNA than single-stranded poly(A).
- The determined site size for binding was 4 base pairs.
Conclusions:
- The lac repressor headpiece exhibits specific binding to double-stranded DNA.
- The binding interaction is sequence-independent for the poly[d(A-T)] polymer.
- The determined site size of 4 base pairs is consistent with other experimental findings.