The identification of catalytically reactive amino acid residues in the active center of DNA-dependent RNA polymerase I

The use of inhibitors that show specificity for only one amino acid has led to the identification of catalytically active amino acid residues in DNA-dependent DNA polymerase. It was found that the enzyme contains a single lysine, arginine and histidine in the active center of the enzyme. Two possible mechanisms have been proposed for the formation of the phosphodiester bond by integrating the various functions of these residues. The identification of these residues in the active center of DNA polymerase gives some supportive evidence that this enzyme and other enzymes of nucleic acid metabolism may have progressed through the same evolutionary path.