Subspecies of DNA polymerase α from calf thymus with different fidelity in copying synthetic template-primers

Abstract
Three different subspecies of DNA polymerase a from calf thymus sedimenting at 9 S, 7 S and 5.7 S have been investigated with respect to their accuracy of in vitro DNA synthesis on poly(dA) (dT)16 and poly d(AT) as template-primers. Our results indicate that the structure of DNA polymerase α has a strong influence on the accuracy of DNA synthesis. The 9 S enzyme shows a mis-incorporation frequency of about 1:100 OOO. An error rate of 1:15 OOO is measured for the 7 S species. The 5.7 S enzyme for which an error rate of 1:3 OOO is determined, has to be considered as error prone. Lowering the rate of DNA synthesis leads to a decrease in fidelity. The single stranded DNA binding protein from E.coli increases the accuracy of the 5.7 S and the 7 S enzyme by a factor of two. Mn2+ decreases the fidelity of all three subspecies in a concentration dependent manner.

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