DNA sequence analysis with a modified bacteriophage T7 DNA polymerase

Proc Natl Acad Sci U S A. 1987 Jul;84(14):4767-71. doi: 10.1073/pnas.84.14.4767.


A chemically modified phage T7 DNA polymerase has three properties that make it ideal for DNA sequencing by the chain-termination method. The enzyme is highly processive, catalyzing the polymerization of thousands of nucleotides without dissociating. By virtue of the modification the 3' to 5' exonuclease activity is eliminated. The modified polymerase efficiently uses nucleotide analogs that increase the electrophoretic resolution of bands in gels. Consequently, dideoxynucleotide-terminated fragments have highly uniform radioactive intensity throughout the range of a few to thousands of nucleotides in length. There is virtually no background due to terminations at pause sites or secondary-structure impediments. Processive synthesis with dITP in place of dGTP eliminates band compressions, making possible the unambiguous determination of sequences from a single orientation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Base Sequence
  • DNA, Recombinant / analysis
  • DNA, Viral / analysis
  • DNA-Directed DNA Polymerase* / metabolism
  • Deoxyribonucleotides / metabolism
  • Exodeoxyribonucleases
  • Free Radicals
  • Nucleotide Mapping / methods*
  • Oxidation-Reduction
  • Protein Multimerization
  • T-Phages / enzymology*
  • Thioredoxins / metabolism
  • Viral Proteins* / metabolism


  • DNA, Recombinant
  • DNA, Viral
  • Deoxyribonucleotides
  • Free Radicals
  • Viral Proteins
  • Thioredoxins
  • bacteriophage T7 induced DNA polymerase
  • DNA-Directed DNA Polymerase
  • Exodeoxyribonucleases