Bacteriophage-T4 and Micrococcus luteus UV endonucleases are not endonucleases but beta-elimination and sometimes beta delta-elimination catalysts. |
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Authors: | V Bailly B Sente and W G Verly |
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Institution: | Biochimie, Faculté des Sciences, Université de Liège, Belgium. |
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Abstract: | 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. |
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