[Conditions for specific oligoribonucleotide binding with E. coli RNA-polymerase].

RNA polymerase of E. coli (EC 2.7.7.6) is able to bind certain oligoribonucleotides with the length greater than or equal to 5 from the corresponding isoplith mixtures (Knorre V.L., Vasilenko S.V., Salganik R.I., FEBS Letters 30, 229, 1973). It has been shown in this study that all pentaribonucleotides able to be bound by RNA polymerase can be extracted from the random mixture by the enzyme saturation procedure. Loosely and tightly bound pentaribonucleotides subfractions were isolated and each was separated by chromatography into 3-4 isopliths. Blocking of the enzyme SH groups by p-chloromercurium benzoate (10(-3) M) and denaturation by urea (6.3 M) prevent formation of the enzyme-pentaribonucleotides complexes. Complexes are destroyed by heat denaturation. Removal of sigma-subunit does not influence the enzyme capacity for pentaribonucleotides binding.