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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
9
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pubmed:dateCreated |
1976-7-6
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pubmed:abstractText |
Two enzyme activities which release nucleotides preferentially from the 5' termini of DNA were found in T4-infected Escherichia coli. Since no corresponding activities were found in uninfected cells, the activities appeared to be induced by T4. Both activities are capable of excising pyrimidine dimers from ultraviolet-irradiated DNA which has been treated with T4 endonuclease V. One of the activities , referred to as T4 exonuclease B, was purified 400-fold from an extract of T4v 1- infected cells. The enzyme initiates hydrolysis of DNA specifically at the 5' termini to yield products which are mainly oligonucleotides of varying length. The hydrolysis reaction proceeds in a limited manner. The enzyme shows optimal activity at pH 7.0 and absolutely requires Mg2+. The molecular weight of the enzyme , as estimated by gel filtration, is approximately 35,000. Another activity, referred to as T4 exonuclease C, was purified 240-fold from the extract. This activity also excises pyrimidine dimers from ultraviolet-irradiated, incised DNA and releases nucleotides at 5' termini. It has a pH optimum at 7.5 and requires Mg2+. The molecular weight of the enzyme is approximately 20,000.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
10
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pubmed:volume |
251
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2613-9
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pubmed:dateRevised |
2000-12-18
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pubmed:meshHeading |
pubmed-meshheading:4453-Coliphages,
pubmed-meshheading:4453-DNA,
pubmed-meshheading:4453-Deoxyribonucleases,
pubmed-meshheading:4453-Enzyme Activation,
pubmed-meshheading:4453-Escherichia coli,
pubmed-meshheading:4453-Exonucleases,
pubmed-meshheading:4453-Hydrogen-Ion Concentration,
pubmed-meshheading:4453-Kinetics,
pubmed-meshheading:4453-Magnesium,
pubmed-meshheading:4453-Molecular Weight,
pubmed-meshheading:4453-Radiation Effects,
pubmed-meshheading:4453-Ultraviolet Rays
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pubmed:year |
1976
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pubmed:articleTitle |
5' leads to 3'-Exonucleases of bacteriophage T4.
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pubmed:publicationType |
Journal Article
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