• Title/Summary/Keyword: Chemical mutagenesis

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Gene-Specific Repair of 6-4 Photoproducts in Trichothiodystrophy Cells

  • Nathan, Sheila;Van Hoffen, Anneke;Mullenders, Leon H.F.;Mayne, Lynne V.
    • BMB Reports
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    • v.32 no.6
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    • pp.554-560
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    • 1999

  • TTD1BI cells are non-hypersensitive to UV irradiation and perform normal genome repair of pyrimidine dimers but fail to excise 6-4 photoproducts and, concomitantly, are unable to restore RNA synthesis levels following UV irradiation. This pointed to a detect in gene-specific repair and this study was undertaken to examine repair of 6-4 photoproducts at the gene-level. The results indicated a defect in gene-specific repair of 6-4 photoproducts in active genes, although strand-specificity of 6-4 photoproduct removal was essentially similar to that of normal cells. These findings indicate that the near normal UV resistance of TTD1BI cells may be due to the inability of these cells to remove DNA lesions preferentially, as well as to the cells opting out of the cell cycle to repair damage before resuming replication.

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Optimization of Programmed Suppression in a Cell-Free Protein Synthesis System with Unnatural Amino Acid S-(2-Nitrobenzyl)cysteine

  • HYUN JOO;KANG, TAEK JIN;HUI KYOUNG SONG;JIN HO AHN;CHA YONG CHOI
    • Journal of Microbiology and Biotechnology
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    • v.13 no.3
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    • pp.344-347
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    • 2003

  • Unnatural amino acid S-(2-nitrobenzyl)cysteine was incorporated into human erythropoietin by using a programmed suppression of nonsense codon in a cell-free protein synthesis system. Several controlling factors affecting the operational efficiency of the suppression were investigated and optimized. The amount of suppressor tRNA and the concentration of $Mg^2+$ were crucial not only for the efficiency but also for the control of the exact suppression. In addition, some general optimization factor are reported in order to improve the efficiency in an unnatural amino acid mutagenesis.

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