Exonuclease VII of Escherichia coli

  • John W. Chase
  • Charles C. Richardson
Part of the Basic Life Sciences book series


A new exonuclease of Escherichia coli K12, exonuclease VII, has been purified 1700-fold and characterized. The enzyme is specific for single-stranded DNA and can initiate hydrolysis at both 5′ and 3′ termini. It is also capable of thyminedimer excision in vitro. The limit products of the reaction are oligonucleotides, predominantly in the range of tetramers to dodecamers. DNA is hydrolyzed by the enzyme in a processive fashion. Mutants of E. coli have been isolated having reduced levels of exonuclease VII activity in crude extracts. Mapping studies place the exonuclease VII locus between 45 and 56 minutes on the E. coli K12 linkage map.


Exonuclease Activity Endonuclease Activity Standard Reaction Mixture Thymine Dimer Alkaline Sucrose Gradient 


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Copyright information

© Plenum Press, New York 1975

Authors and Affiliations

  • John W. Chase
    • 1
  • Charles C. Richardson
    • 1
  1. 1.Department of Biological ChemistryHarvard Medical SchoolBostonUSA

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