Human uracil DNA N-glycosidase: studies in normal and repair defective cultured fibroblasts

• Published in: Nucleic acids research 1978-01, Vol.5 (1), p.117-125
• Main Authors: Kuhnlein, Urs, Lee, Betty, Linn, Stuart
• Format: Article
• Language: English
• Subjects: Apurinic Acid; Ataxia Telangiectasia - enzymology; Deoxyuracil Nucleotides; DNA; DNA Repair; Endonucleases - metabolism; Humans; Kinetics; N-Glycosyl Hydrolases - metabolism; Xeroderma Pigmentosum - enzymology; Xeroderma Pigmentosum - genetics
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/5.1.117

Uracil DNA N-glycosidase, an enzyme which participates in the excision of uracil from DNA, was measured in extracts from fibroblast lines cultured from normal subjects, from several subjects with the genetic disease xeroderma pigmentosum, and from a subject with ataxia telangiectasia. The cell lines representative of complementation groups A and D of xeroderrna pigmentosum and of ataxia telangiectasia had roughly the same level of activity as did the normal cells. On the other hand, cells from two xeroderma pigmentosum variants (XP4BE and XP13BE) had roughly half the normal level of activity, and cells from the heterozygous mother of XP4BE had an interme diate level of activity. In spite of these quantitative differences, no systematic alterations in reaction characteristics, apparent Km for substrate, or purification characteristics were noted for enzyme from any of the lines. Thus a causal relationship, if any, between levels of activity and the disease symptoms is equivocal.