| Literature DB >> 3684600 |
S Riazuddin1, A Athar, A Sohail.
Abstract
Three peaks of methyltransferase activity specific for MNNG alkylated DNA have been identified from extracts of chemically adapted M. luteus. They are designated as TI to TIII in order to their elution from a Sephadex G-75 column. The first one of these peaks has been purified to homogeneity. TI, is an inducible, unusually salt resistant, heat labile protein which corrects O6-methylguanine in alkylated DNA by the transfer of the O6-alkyl group to a cysteine amino acid in the TI protein. There is a stoichiometric relationship between the loss of O6-methylguanine from the DNA and the production of S-methylcysteine. Partially purified TII & TIII proteins show specificity for O4-alkylthymine and methyl phosphotriesters respectively. The mode of repair by the isolated methyltransferases is similar yet there is no competition for substrate specificity. The apparent molecular weights of TI, TII & TIII proteins are 31Kd, 22Kd, and 13Kd respectively.Entities:
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Year: 1987 PMID： 3684600 PMCID： PMC306481 DOI： 10.1093/nar/15.22.9471
Source DB: PubMed Journal: Nucleic Acids Res ISSN： 0305-1048 Impact factor: 16.971