title: Co-operativity value of DNA RecA protein interaction. Influence of the protein quaternary structure on the binding analysis.
abstract: We show that an erroneous estimation of the quaternary structure of free protein distorts the quantitative analysis of its interaction with DNA, affecting especially the co-operativity value found. This could explain the discrepancy reported for the co-operativity value of the RecA-DNA interaction. The large cluster observed by electron microscopy indicates a very high co-operativity, whereas analysis of the binding isotherm indicates a moderate one, on the assumption of monomer. But if RecA is a large oligomer, the latter analysis would give a much higher co-operativity value and the former a smaller one, and they would be in accordance. Our sedimentation and light-scattering experiments suggest an oligomerization of about 30-mer or more, and support this explanation.
mesh_terms: D000494:Allosteric Regulation; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D011938:Rec A Recombinases / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D046911:Macromolecular Substances; D011938:Rec A Recombinases