Primed and unprimed synthesis of poly (dA-dT) by calf thymus DNA polymerase alpha

Abstract

The primed and unprimed synthesis of poly(dA-dA-dT) by calf thymus DNA polymerase alpha (DNA nucleotidyltransferase; deoxynucleoside triphosphate: DNA deoxynucleotidyltransferase EC 2.7.7.7) has been compared to replication of activated DNA. Synthesis of poly(dA-dT) by alpha-polymerase is both autocatalytic and exponential. The rate of synthesis of poly(dA-dT) is markedly affected by the Mg2+ concentration and has a higher temperature optimum than replication of activated DNA, implicating "slippage" as a necessary part of poly(dA-dT) replication. Calf thymus 24,000-dalton unwinding protein influences poly(dA-dT) synthesis by increasing both the exponential rate constant and the rate of linear synthesis. Single-stranded template poly(dA-dT) is provided alpha-polymerase by both "strand slippage" and melting by unwinding protein.