PubMed:8276875 JSONTXT

{"project":"sentences","denotations":[{"id":"T1","span":{"begin":0,"end":109},"obj":"Sentence"},{"id":"T2","span":{"begin":110,"end":418},"obj":"Sentence"},{"id":"T3","span":{"begin":419,"end":582},"obj":"Sentence"},{"id":"T4","span":{"begin":583,"end":788},"obj":"Sentence"},{"id":"T5","span":{"begin":789,"end":879},"obj":"Sentence"},{"id":"T6","span":{"begin":880,"end":1063},"obj":"Sentence"},{"id":"T7","span":{"begin":1064,"end":1190},"obj":"Sentence"},{"id":"T1","span":{"begin":0,"end":109},"obj":"Sentence"},{"id":"T2","span":{"begin":110,"end":418},"obj":"Sentence"},{"id":"T3","span":{"begin":419,"end":582},"obj":"Sentence"},{"id":"T4","span":{"begin":583,"end":788},"obj":"Sentence"},{"id":"T5","span":{"begin":789,"end":879},"obj":"Sentence"},{"id":"T6","span":{"begin":880,"end":1063},"obj":"Sentence"},{"id":"T7","span":{"begin":1064,"end":1190},"obj":"Sentence"}],"namespaces":[{"prefix":"_base","uri":"http://pubannotation.org/ontology/tao.owl#"}],"text":"Repair of O6-methylguanine and O4-methylthymine by the human and rat O6-methylguanine-DNA methyltransferases.\nIn order to compare the ability of the human and rat O6-methylguanine-DNA methyltransferases (transferases) to repair in vitro O6-methylguanine (O6-MeGua) and O4-methylthymine (O4-MeThy) residues, which are two mutagenic DNA adducts formed by alkylating agents, we have purified both proteins to homogeneity. Gel electrophoresis of the proteins shows that the O4-MeThy repair is due to the transfer of the methyl group from the alkylated base to the transferase molecules. However, both proteins repair with different efficiencies the O6-MeGua and O4-MeThy residues present in alkylated DNA, poly[d(G.C)], poly(dG.dC), or in alkylated poly[d(A.T)] and poly(dA.dT), respectively. Reaction of both proteins with either methylated residues follows a second-order kinetics. The rate constants are 1 x 10(9) M-1 min-1 for both proteins acting on O6-MeGua and 4.8 x 10(6) or 1.8 x 10(5) M-1 min-1 for the rat or human protein acting on O4-MeThy, respectively. The activity of the mammalian transferases on O4-MeThy present in a poly(dA.dT) substrate is inhibited by double-stranded DNA."}

{"project":"NCBITAXON","denotations":[{"id":"T1","span":{"begin":55,"end":60},"obj":"OrganismTaxon"},{"id":"T2","span":{"begin":65,"end":68},"obj":"OrganismTaxon"},{"id":"T4","span":{"begin":149,"end":154},"obj":"OrganismTaxon"},{"id":"T5","span":{"begin":159,"end":162},"obj":"OrganismTaxon"},{"id":"T7","span":{"begin":1009,"end":1012},"obj":"OrganismTaxon"},{"id":"T9","span":{"begin":1016,"end":1021},"obj":"OrganismTaxon"}],"attributes":[{"id":"A1","pred":"db_id","subj":"T1","obj":"9606"},{"id":"A2","pred":"db_id","subj":"T2","obj":"10114"},{"id":"A3","pred":"db_id","subj":"T2","obj":"10116"},{"id":"A4","pred":"db_id","subj":"T4","obj":"9606"},{"id":"A5","pred":"db_id","subj":"T5","obj":"10114"},{"id":"A6","pred":"db_id","subj":"T5","obj":"10116"},{"id":"A7","pred":"db_id","subj":"T7","obj":"10114"},{"id":"A8","pred":"db_id","subj":"T7","obj":"10116"},{"id":"A9","pred":"db_id","subj":"T9","obj":"9606"}],"text":"Repair of O6-methylguanine and O4-methylthymine by the human and rat O6-methylguanine-DNA methyltransferases.\nIn order to compare the ability of the human and rat O6-methylguanine-DNA methyltransferases (transferases) to repair in vitro O6-methylguanine (O6-MeGua) and O4-methylthymine (O4-MeThy) residues, which are two mutagenic DNA adducts formed by alkylating agents, we have purified both proteins to homogeneity. Gel electrophoresis of the proteins shows that the O4-MeThy repair is due to the transfer of the methyl group from the alkylated base to the transferase molecules. However, both proteins repair with different efficiencies the O6-MeGua and O4-MeThy residues present in alkylated DNA, poly[d(G.C)], poly(dG.dC), or in alkylated poly[d(A.T)] and poly(dA.dT), respectively. Reaction of both proteins with either methylated residues follows a second-order kinetics. The rate constants are 1 x 10(9) M-1 min-1 for both proteins acting on O6-MeGua and 4.8 x 10(6) or 1.8 x 10(5) M-1 min-1 for the rat or human protein acting on O4-MeThy, respectively. The activity of the mammalian transferases on O4-MeThy present in a poly(dA.dT) substrate is inhibited by double-stranded DNA."}

{"project":"CL-cell","denotations":[{"id":"T1","span":{"begin":702,"end":706},"obj":"Cell"},{"id":"T3","span":{"begin":716,"end":720},"obj":"Cell"},{"id":"T5","span":{"begin":745,"end":749},"obj":"Cell"},{"id":"T7","span":{"begin":762,"end":766},"obj":"Cell"},{"id":"T9","span":{"begin":1132,"end":1136},"obj":"Cell"}],"attributes":[{"id":"A1","pred":"cl_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/CL:0000096"},{"id":"A2","pred":"cl_id","subj":"T1","obj":"http://purl.obolibrary.org/obo/CL:0000775"},{"id":"A3","pred":"cl_id","subj":"T3","obj":"http://purl.obolibrary.org/obo/CL:0000096"},{"id":"A4","pred":"cl_id","subj":"T3","obj":"http://purl.obolibrary.org/obo/CL:0000775"},{"id":"A5","pred":"cl_id","subj":"T5","obj":"http://purl.obolibrary.org/obo/CL:0000096"},{"id":"A6","pred":"cl_id","subj":"T5","obj":"http://purl.obolibrary.org/obo/CL:0000775"},{"id":"A7","pred":"cl_id","subj":"T7","obj":"http://purl.obolibrary.org/obo/CL:0000096"},{"id":"A8","pred":"cl_id","subj":"T7","obj":"http://purl.obolibrary.org/obo/CL:0000775"},{"id":"A9","pred":"cl_id","subj":"T9","obj":"http://purl.obolibrary.org/obo/CL:0000096"},{"id":"A10","pred":"cl_id","subj":"T9","obj":"http://purl.obolibrary.org/obo/CL:0000775"}],"text":"Repair of O6-methylguanine and O4-methylthymine by the human and rat O6-methylguanine-DNA methyltransferases.\nIn order to compare the ability of the human and rat O6-methylguanine-DNA methyltransferases (transferases) to repair in vitro O6-methylguanine (O6-MeGua) and O4-methylthymine (O4-MeThy) residues, which are two mutagenic DNA adducts formed by alkylating agents, we have purified both proteins to homogeneity. Gel electrophoresis of the proteins shows that the O4-MeThy repair is due to the transfer of the methyl group from the alkylated base to the transferase molecules. However, both proteins repair with different efficiencies the O6-MeGua and O4-MeThy residues present in alkylated DNA, poly[d(G.C)], poly(dG.dC), or in alkylated poly[d(A.T)] and poly(dA.dT), respectively. Reaction of both proteins with either methylated residues follows a second-order kinetics. The rate constants are 1 x 10(9) M-1 min-1 for both proteins acting on O6-MeGua and 4.8 x 10(6) or 1.8 x 10(5) M-1 min-1 for the rat or human protein acting on O4-MeThy, respectively. The activity of the mammalian transferases on O4-MeThy present in a poly(dA.dT) substrate is inhibited by double-stranded DNA."}