Preparation and characterization of large amounts of restriction fragments containing the E. coli lac control elements.

Large quantities of pure DNA fragments (789, 203 and 95 bp in length) containing the Escherichia coli lac controlling elements (operator, promoter, CRP binding site) were prepared from appropriate recombinant plasmids. High pressure liquid chromatography on RPC-5 or preparative sucrose gradient centrifugation was used to fractionate the pVH51 vector from the inserts. The fragments had few, if any, nicks or depurinated sites, and the majority of the fragment ends were intact. Absorbance-temperature profiles on the fragments showed multiphasic transitions.