Specific modification of Escherichia coli RNA polymerase with monomercury derivative of fluorescein acetate.

The method of specific modification of RNA polymerase with a monomercuric fluorescein derivative, fluorescein-monomercuriacetate (FMMA), is proposed. Under an appropriate condition of modification, FMMA is capable of mercaptid bonding with one of the alpha-subunits. It is shown that covalent modification with FMMA does not affect the kinetic parameters (KB and k2) of RNA synthesis nor does it lead to the inhibition of the overall RNA synthesis. The spectral characteristics of FMMA covalently bound to RNA polymerase were found to be sensitive to some temperature-induced conformational alterations of RNA polymerase, indicating that the labeled enzyme allows study of conformational behaviour of RNA polymerase during its functioning.