AFFINITY LABELING OF THE 3'-OH TERMINAL BINDING-SITE OF THE RIBONUCLEIC-ACID CHAIN ON DEOXYRIBONUCLEIC-ACID DEPENDENT RIBONUCLEIC-ACID POLYMERASE FROM ESCHERICHIA-COLI

Nucleoside triphosphates modified at the 3'-OH are chain terminators for RNA polymerase. They form inactive ternary complexes with the enzyme, poly(dT), and oligoadenylate, the stabilities of which depend upon the length of the oligonucleotide. Employing [5'-32P]p(Ap)10A, together with the reactive analogues 3'-(bromoacetamido)-3/-deoxyadenosine triphosphate or 3'-(isothiocyanato)-2',3'-dideoxy-adenosine triphosphate, as well as 3'-amino-3'-deoxyadenosine triphosphate, followed by cross-linking with glyoxal, we labeled RNA polymerase primarily at the β' subunit. The latter therefore appears to contain at least in part the 3'-OH terminus of the nascent RNA chain when the enzyme is in the form of the ternary complex. © 1979, American Chemical Society. All rights reserved.