YEAST RNA-POLYMERASE .1. A EUKARYOTIC ZINC METALLOENZYME
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1976
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Abstract
Microwave excitation spectrometry and metal binding inhibition studies showed that Zn is a catalytically essential component of the highly purified RNA polymerase I from yeast, the 1st eukaryotic RNA polymerase I available in quantities sufficient for such studies. It contained 2.4 g-atom of Zn based on a MW of 6.5 .times. 105. Cu, Fe, Mn and Mg were absent, i.e., below the limits of detection, 10-3-10-14 g-atoms. A number of derivatives of 1,10-phenanthroline reversibly inhibited the polymerase catalyzed reaction, apparently by forming a ternary polymerase.cntdot.Zn.cntdot.OP complex while the nonchelating isomer, 1,7-phenanthroline, was ineffective.