Nucleic Acids Research, 1978, Vol. 5, No. 1 117-125
© 1978
Articles |
Human uracil DNA N-glycosidase: studies in normal and repair defective cultured fibroblasts
Department of Biochemistry, University of California Berkeley, CA 94720, USA
*To whom correspondence should be addressed.
Received September 30, 1977.
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.
Present address: Biophysics Department, B.C. Cancer Foundation, Vancouver, B.C., Canada V5Z 3K3.
Present address: Harvard Medical School, Boston, Mass, 02115