Utilization of 2′-Deoxy-6-thioguanosine 5′-Triphosphate in DNA Synthesis in vitro by DNA Polymerase α from Calf Thymus

Abstract

Chemically synthesized β-2′-deoxy-6-thioguanosine 5′-triphosphate, a putative active form of β-2′-deoxy-6-thioguanosine, was used efficiently as a substrate for DNA synthesis catalyzed by DNA polymerase α from calf thymus. The deoxy-thioguanylate was incorporated into DNA by replacing deoxy-guanylate and supported the further elongation of DNA chains on activated calf thymus DNA. In contrast, DNA polymerase β used β-2′-deoxy-6-thioguanosine 5′-triphosphate at a much lower rate. The reaction product of DNA polymerase α, i.e., 6-thioguanine-containing DNA, adsorbed specifically to the organomercurial agarose column, and showed a peak of UV absorption at 342 nm, which is characteristic of thioguanine.