title: An altered apurinic DNA endonuclease activity in group A and group D xeroderma pigmentosum fibroblasts.
abstract: Endonuclease activity upon depurinated DNA was measured in extracts of cultured fibroblasts from xeroderma pigmentosum patients. Cell lines from complementation groups A, B, C, E, and the XP-variant had slightly reduced levels of activity, but cell lines from complementation group D had one-sixth of the normal activity. An altered pH dependence and a higher apparent Km for substrate in D-cell lines indicate that the remaining activity is also qualitatively different from the activity found in normal cells. A higher Km was also found in cell lines from the A-complementation group but not in cell lines from the C-complementation group. These defects in apurinic DNase might account for the neurological disorders in patients from the D- and the A-complementation groups.
mesh_terms: D001080:Apurinic Acid / Q000378:metabolism*; D002478:Cells, Cultured; D004260:DNA Repair; D004720:Endonucleases / Q000378:metabolism*; D005816:Genetic Complementation Test; D006801:Humans; D007700:Kinetics; D011119:Polynucleotides / Q000378:metabolism*; D014983:Xeroderma Pigmentosum / Q000201:enzymology* / Q000235:genetics
chemical_list: D011119:Polynucleotides; D001080:Apurinic Acid; D004720:Endonucleases