[Cooperative non-specific binding of the cyclic adenosine 3'--5'-monophosphate receptor protein (CRP) from Escherichia coli to double-stranded thymus and lambda pgal DNA].

Either free or combined with cAMP, CRP binds cooperatively to double-stranded thymus and lambda pgal DNA. The affinity of CRP for both DNAs in these non-specific interactions is increased by cAMP without noticeable change in the degree of cooperativity. Values of the intrinsic association constant, cooperativity parameter, and site size of DNA were determined from ultracentrifugal investigations under near-physiological ionic conditions.