The elongation of mismatched primers by DNA polymerase alpha from calf thymus

Nucleic Acids Res. 1983 Oct 25;11(20):7251-60. doi: 10.1093/nar/11.20.7251.

Abstract

The ability of the 9S and 5.7S DNA polymerase alpha 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 (dT)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 reduces 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • DNA Polymerase II / metabolism*
  • Kinetics
  • Magnesium / pharmacology
  • Manganese / pharmacology
  • Structure-Activity Relationship
  • Substrate Specificity
  • Templates, Genetic
  • Thymus Gland / enzymology*

Substances

  • Manganese
  • DNA Polymerase II
  • Magnesium