TY - JOUR
T1 - Kinetics of repair of O6-methylguanine in DNA by O6-methylguanine-DNA methyltransferase in, vitro and in, vivo
AU - Scicchitano, David
AU - Pegg, Anthony E.
N1 - Funding Information:
This research was supported by grant CA-18138 and lP30-CA-18450 from the National Cancer Institute. The authors also wish to thank Mrs. Bonnie Merlin0 for typing the manuscript.
PY - 1982/12/15
Y1 - 1982/12/15
N2 - The demethylation of O6-methylguanine in double stranded DNA catalyzed by rat liver O6-methylguanine-DNA transmethylase was found to proceed much more rapidly when the DNA substrate was methylated to a high extent. When the content of O6-methylguanine in DNA was equal to 1 in 2000 guanines, the reaction was 90% complete within 2 min, but when the content was 1 in 500,000 it required 27 min at 37°C. These results suggest that the repair protein either moves along the DNA substrate or else has little selectivity for binding specifically to the sites containing O6-methylguanine rather than to the normal DNA. The repair of O6-methylguanine in rat liver in, vivo occurred at rates comparable to those seen in, vitro with the substrates alkylated to low extents and was virtually complete within 3 hours. These results provide strong evidence that this protein is the factor responsible for O6-methylguanine removal in, vivo and explain the wide variation in time courses reported in the literature since substrates methylated to greatly different extents have been used for such experiments.
AB - The demethylation of O6-methylguanine in double stranded DNA catalyzed by rat liver O6-methylguanine-DNA transmethylase was found to proceed much more rapidly when the DNA substrate was methylated to a high extent. When the content of O6-methylguanine in DNA was equal to 1 in 2000 guanines, the reaction was 90% complete within 2 min, but when the content was 1 in 500,000 it required 27 min at 37°C. These results suggest that the repair protein either moves along the DNA substrate or else has little selectivity for binding specifically to the sites containing O6-methylguanine rather than to the normal DNA. The repair of O6-methylguanine in rat liver in, vivo occurred at rates comparable to those seen in, vitro with the substrates alkylated to low extents and was virtually complete within 3 hours. These results provide strong evidence that this protein is the factor responsible for O6-methylguanine removal in, vivo and explain the wide variation in time courses reported in the literature since substrates methylated to greatly different extents have been used for such experiments.
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U2 - 10.1016/0006-291X(82)92038-1
DO - 10.1016/0006-291X(82)92038-1
M3 - Article
C2 - 7187611
AN - SCOPUS:0020484504
SN - 0006-291X
VL - 109
SP - 995
EP - 1001
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 3
ER -