Bacteriophage-T4 and Micrococcus luteus UV endonucleases are not endonucleases but beta-elimination and sometimes beta delta-elimination catalysts.
Bacteriophage-T4 UV endonuclease nicks the C(3')-O-P bond 3' to AP (apurinic or apyrimidinic) sites by a beta-elimination reaction. The breakage of this bond is sometimes followed by the nicking of the C(5')-O-P bond 5' to the AP site, leaving a 3'-phosphate end; delta-elimination is proposed as a mechanism to explain this second reaction. The AP site formed when this enzyme acts on a pyrimidine dimer in a polynucleotide chain undergoes the same nicking reactions. Micrococcus luteus UV endonuclease also nicks the C(3')-O-P bond 3' to AP sites by a beta-elimination reaction. No subsequent delta-elimination was observed, but this might be due to the presence of 2-mercaptoethanol in the enzyme preparation.
Bailly
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Biochimie, Faculté des Sciences, Université de Liège, Belgium.
Sente
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Verly
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D002384:Catalysis; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000378:metabolism*; D008837:Micrococcus / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000378:metabolism*; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D009841:Oligonucleotides / Q000378:metabolism; D013604:T-Phages / Q000201:enzymology*
D009097:Multienzyme Complexes; D009841:Oligonucleotides; C032219:UV endonuclease; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); D009699:N-Glycosyl Hydrolases; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase