Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A deoxyinosine-specific endonuclease, deoxyinosine 3'-endonuclease (Yao, M., Hatahet, Z., Melamede, R. J., and Kow, Y. W. (1994) J. Biol. Chem. 269, 16260-16268), from Escherichia coli was found to recognize mismatches in DNA. Using DNA duplexes containing a unique mismatch, the enzyme was found to hydrolyze the second phosphodiester bond 3' to the mismatch. The cleavage efficiency of deoxyinosine 3'-endonuclease on mismatch-containing DNA was affected by the nature of the mismatches. The cleavage activity was also affected by the sequence context surrounding the mismatches. The presence of a G/C or C/G pair immediately 3' or 5' to the mismatch substantially reduced the ability of the enzyme to nick the mismatch-containing DNA. The presence of two G/C pairs, one 5' and the other 3' to the mismatch, abolishes the ability of the enzyme to recognize the mismatch. Interestingly, deoxyinosine 3'endonuclease showed strong strand specificity on DNA containing mismatches, and only one strand of the mismatch-containing DNA was nicked by the enzyme. This strand specificity of mismatch cleavage was not affected by the nature of the mismatch. Preliminary data suggest that the strand specificity is terminus dependent; the enzyme cleaves the strand with the mismatch closer to its 5' terminus. However, when DNA duplexes containing deoxyinosine were used as substrates, deoxyinosine 3'-endonuclease cleaved exclusively the strand containing deoxyinosine. Deoxyinosine 3'-endonuclease also cleaved single-stranded DNA containing deoxyinosine, but not DNA containing normal deoxynucleotides or deoxynebularine, suggesting the enzyme uses different mechanisms of recognition for deoxyinosine and mismatches in DNA.
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PMID:Strand-specific cleavage of mismatch-containing DNA by deoxyinosine 3'-endonuclease from Escherichia coli. 798 4

We have purified a novel endonuclease from Escherichia coli that recognizes deoxyinosine, a deamination product of deoxyadenosine in DNA. This activity, which we named deoxyinosine 3' endonuclease, is different from the known hypoxanthine DNA N-glycosylases which have been partially characterized in E. coli and other organisms. The enzyme was purified 24,800-fold to apparent homogeneity. SDS- and activity PAGE analyses indicate that the enzyme has an apparent molecular mass of 25 kDa. Deoxyinosine 3' endonuclease recognized deoxyinosine in both single- and double-stranded DNA but exhibited a 4-fold preference for double stranded over single-stranded DNA. In addition to deoxyinosine, the enzyme recognized urea residues and AP sites. Deoxyinosine 3' endonuclease has an obligatory requirement for Mg2+, but other cations such as Co2+ and Mn2+ could partially replace Mg2+. The optimal pH for deoxyinosine 3' endonuclease was around 7.5. In contrast to most of the known repair enzymes, deoxyinosine 3' endonuclease makes an incision at the second phosphodiester bond 3' to a deoxyinosine or AP site, leaving behind the intact lesion on the nicked DNA. Therefore, deoxyinosine 3' endonuclease recognizes, but does not remove, the lesion from the DNA molecule. The biological significance of this novel activity is discussed with reference to other repair activities in E. coli.
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PMID:Purification and characterization of a novel deoxyinosine-specific enzyme, deoxyinosine 3' endonuclease, from Escherichia coli. 820 31

Deoxyinosine 3'-endonuclease, an Escherichia coli repair enzyme that recognizes and cleaves DNA containing deoxyinosine and base mismatches, can cleave heteroduplexes containing a hairpin or unpaired loop. These DNA structures, referred to as insertion/deletion mismatches (IDM), are abnormal intermediate structures generated during replication of repetitive DNA sequences. In addition, the enzyme also cleaved the 5'-single-stranded tails of flap and pseudo-Y DNA structures, suggesting that deoxyinosine 3'-endonuclease is a bacterial functional homologue of human FEN1 and yeast RTH1 nucleases. These biochemical properties suggest that deoxyinosine 3'-endonuclease might be important in the repair of IDM structures generated in lagging strand during DNA replication.
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PMID:Cleavage of insertion/deletion mismatches, flap and pseudo-Y DNA structures by deoxyinosine 3'-endonuclease from Escherichia coli. 894 43