A double antibody radioimmunoassay for canine cardiac cathepsin D.
We have developed a sensitive double antibody radioimmunoassay for measuring canine cardiac cathepsin D. Radioiodinated cathepsin D was prepared by chloramine T oxidation using a highly purified source of enzyme. High avidity antiserum to the canine cardiac enzyme was raised in rabbits. Antibody-bound cathepsin D was separated from free enzyme using goat anti-rabbit IgG second antibody. The least amount of immunoreactive enzyme measurable in the radioimmunoassay was 2.4 ng.cm-3 as determined by antibody titration. The assay was linear for concentrations of enzyme in the range of 10 to 120 ng.cm-3. Within-assay and between-assay variations were 12%. The radioimmunoassay described was used to measure the immunoreactive cathepsin D content of the 100 000 x g supernatant fraction of canine myocardial homogenates.
D000818:Animals; D002402:Cathepsin D; D002403:Cathepsins / Q000032:analysis*; D004285:Dogs; D007457:Iodine Radioisotopes; D009206:Myocardium / Q000201:enzymology*; D011863:Radioimmunoassay / Q000379:methods*
D007457:Iodine Radioisotopes; D002403:Cathepsins; D002402:Cathepsin D