Release of N2,3-ethanoguanine from haloethylnitrosourea-treated DNA by Escherichia coli 3-methyladenine DNA glycosylase II.
3-Methyladenine DNA glycosylase II (Gly II), purified from Escherichia coli cells which carry the plasmid PYN1000, has been tested for its ability to release N2,3-ethanoguanine from DNA modified by the antitumor agent N-[2-chloroethyl-1,2-14C]-N'-cyclohexyl-N-nitrosourea ([14C]CCNU). Gly II has been shown to release N2,3-ethanoguanine in a protein- and time-dependent manner at a rate that exceeds the rate at which this enzyme releases other alkylated bases from [14C]CCNU-modified DNA. This finding widens the known substrate specificity for Gly II to include a modified base which bears an exocyclic ring structure, a class of modifications caused by a variety of chemical carcinogens.
Department of Pharmacology, University of Massachusetts Medical School, Worcester 01655.
Y
Y
Habraken
C A
CA
Carter
M
M
Sekiguchi
D B
DB
Ludlum
D001426:Bacterial Proteins / Q000378:metabolism*; D002250:Carbon Radioisotopes; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D045647:DNA Glycosylases; D004926:Escherichia coli / Q000201:enzymology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D007700:Kinetics; D008130:Lomustine / Q000378:metabolism / Q000494:pharmacology*; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D013379:Substrate Specificity
D001426:Bacterial Proteins; D002250:Carbon Radioisotopes; C071372:N(2),3-ethanoguanine; D006147:Guanine; D008130:Lomustine; D004247:DNA; C021565:3-methyladenine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases