title: Colicin E1 plasmid as a probe for detection and study of anti-dna activity in SLE sera.
abstract: Tritiated colicin E1 plasmid DNA ([3H]DNA) was purified, characterized and developed as a test antigen for study of anti-DNA antibody activity in a modified Farr assay. The homogeneous molecular weight (4.2 X 10(6) daltons), physical state (intact covalently closed circles), and capacity for intrinsic radioactive labeling to a suitable specific activity were all important properties of the plasmid probe. In addition, the ability of the Farr assay to measure primary antigen/antibody interactions made quantitative determinations of anti-double-stranded DNA (dsDNA) antibody activity possible. Sonication of the plasmid resulted in definable fragments which were thermally denatured and used in the measurement of anti-single-stranded DNA (ssDNA) antibody activity. Results from studies in which unlabeled dsDNA, ssDNA, amd free 2'-deoxyribonucleotides were employed to inhibit binding of [3H]DNA by anti-DNA antibodies indicated the presence of 3 distinct anti-DNA specificities in SLE sera.
mesh_terms: D000974:Antibodies, Antinuclear / Q000032:analysis*; D000937:Antigen-Antibody Reactions; D003087:Colicins / Q000276:immunology; D004247:DNA / Q000276:immunology; D004269:DNA, Bacterial / Q000276:immunology; D004277:DNA, Single-Stranded / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D010957:Plasmids
chemical_list: D000974:Antibodies, Antinuclear; D003087:Colicins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004247:DNA