Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
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Gene/Protein
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Enzyme
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Target Concepts:
Gene/Protein
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Enzyme
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Query: EC:3.1.25.1 (
deoxyribonuclease
)
1,471
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The
deoxyribonuclease
specified by the recB and recC genes of Escherichia coli (recBC DNase;
exonuclease V
) has been purified to near homogeneity by a new procedure. Although hydrolysis of even a single nucleotide from a duplex DNA molecule by the pure enzyme is absolutely dependent upon ATP, the extent of phosphodiester hydrolysis is strongly inhibited by ATP concentrations of 0.2 mm or greater, and the initial rate is unaffected. Under these conditions, the extent of DNA hydrolysis is proportional to enzyme concentration. In contrast, neither the rate nor the extent of hydrolysis of single-stranded DNA nor ATP is affected by high concentrations of ATP. The amount of large single-stranded polynucleotide generated by the action of the recBC DNase increases as the ATP concentration increases and, at 0.5 mM ATP, becomes equivalent to the amount of acid-soluble nucleotide formed. These findings suggest that high intracellular concentrations of ATP affect the mechanism of the recBC DNase so as to limit the extent of hydrolysis of duplex DNA, while at the same time favoring the formation of single-stranded regions within the duplex. Such regions may be essential intermediates in the recombination process.
...
PMID:On the role of ATP in phosphodiester bond hydrolysis catalyzed by the recBC deoxyribonuclease of Escherichia coli. 31 95
Exonuclease V (the recBC enzyme) of Escherichia coli can release pyrimidine dimers from ultraviolet-irradiated linear duplex DNA though it acts more slowly on irradiated DNA than on non-irradiated DAN. However, close circular lambda-dv DNA or phi X174 replicative form I DNA is not attacked by
exonuclease V
even though the DNA has been irradiated and treated with
T4 endonuclease V
to produce single-stranded breaks at the 5'-side of pyrimidine dimers. When irradiated circular DNA, previously nicked by
T4 endonuclease V
, is briefly exposed to elevated temperature, the DAN becomes susceptible to the action of
exonuclease V
, and pyrimidine dimers are selectively released. The increased susceptibility to
exonuclease V
may be resulted from locarized denaturation, or "fraying" of the 5'-termini at the nicks. The preferential release of pyrimidine dimers was observed when irradiated DNA, treated with
T4 endonuclease V
, was incubated with crude extracts of Escherichia coli. The activity was found in various strains defective in
exonuclease V
and/or DNA polymerase I.
...
PMID:Action of exonuclease V (the recBC enzyme) on ultraviolet-irradiated DNA. 109 Dec 99
A novel
deoxyribonuclease
,
exonuclease V
, has been purified approximately 30,000-fold from Saccharomyces cerevisiae. Exonuclease V is localized in the nucleus. The nuclease degrades single-stranded, but not double-stranded, DNA from the 5'-end. The products of exonuclease action are dinucleotides, except the 3'-terminal tri- and tetranucleotides which are not degraded. Studies with synthetic oligo- and polynucleotides with specified sequence elements showed that
exonuclease V
cleaves off dinucleotides as primary digestion products. Thus, the polymers (pT)9pA(pT)n and (pT)10pA(pT)n yielded pTpA and pApT as digestion products, respectively. Removal of the 5'-terminal phosphate from the DNA substrate results in reduced binding of the enzyme to the substrate. In addition, the initial hydrolytic cut by
exonuclease V
on the dephosphorylated substrate produces a mixture of dinucleoside monophosphates and trinucleoside diphosphates. The enzyme is processive in action.
...
PMID:Exonuclease V from Saccharomyces cerevisiae. A 5'----3'-deoxyribonuclease that produces dinucleotides in a sequential fashion. 328 46
