The elongation of mismatched primers by DNA polmerasea from α calf thymus

• Published in: Nucleic acids research Vol. 11; no. 20; pp. 7251 - 7260
• Main Authors: Reckmann, Bernd, Grosse, Frank, Krauss, Gerhard
• Format: Journal Article
• Language: English
• Published: Oxford University Press 25.10.1983
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/11.20.7251

The ability of the 9S and 5.7S DNA polymerase α subspecies from calf thymus in elongating a mismatched primer terminus has been investigated. With poly(dA) as template, the elongation rate for (dT)8dg, (dT)8dc and (dI)10dGdT is 20-fold lower for the 9S enzyme and 5-fold lower for the 5.7S enzyme as compared to (dT)10. The presence of a second mismatch at the primer terminus redu the elongation rate further by a factor of two. Exonucleolytic excision of the mismatches can be excluded. With (dT)8dg (dT)n as primer we show, that at least five T-residues have to follow the mismatch in order to establish the elongation rate of a perfectly paired primer. The KM value for (dT)10 dG as primer is 400 nM as compared to 10 nM for (dT)10 Addition of Mn2+ increases the relative efficiency of elongation of the mismatched primers.