Partial purification of a human DNA glycosylase acting on the cyclic carcinogen adduct 1,N6-ethenodeoxyadenosine.
We previously reported that a variety of human cells and tissues contained a Mr35,000 DNA-binding protein which selectively recognized a single 1,N6-ethenoadenine in a defined 25-base double-stranded oligonucleotide (B. Rydberg et al., Proc. Natl. Acad. Sci. USA, 88: 6839-6842, 1991). We now demonstrate that incubation of the same duplex with 50-fold partially purified binding protein from human placenta results in release of the free 1,N6-ethenoadenine base, indicative of DNA glycosylase action. This enzyme activity appears unique in that it excises a cyclic adduct resulting from a known human carcinogen.
Rydberg
B
B
Division of Cell and Molecular Biology, Donner Laboratory, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
Qiu
Z H
ZH
Dosanjh
M K
MK
Singer
B
B
D000225:Adenine / Q000031:analogs & derivatives* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003839:Deoxyadenosines / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification*
D003839:Deoxyadenosines; C004981:1,N(6)-ethenoadenine; C032221:1,N(6)-ethenodeoxyadenosine; D009699:N-Glycosyl Hydrolases; D000225:Adenine