title: A radioimmunoassay for total human cathepsin B.
abstract: A radioimmunoassay for human cathepsin B is described, which demonstrates the usefulness of protein A-bearing Staphylococcus aureus as an immunosorbent in a system where the primary antibody IgG has a low binding affinity for protein A. The removal of bound antigen from the incubation mixture is achieved by the use of a rabbit second step antiserum which confers high binding affinity for protein A to the primary immune complex. This method, as employed in the assay for human cathepsin B, is very reproducible and economical for large numbers of samples. The use of a monospecific antiserum to human cathepsin B and slightly alkaline assay conditions allow the determination of total cathepsin B protein in tissue fluids which is not possible by enzyme activity determination.
mesh_terms: D001667:Binding, Competitive; D002401:Cathepsin B; D002403:Cathepsins / Q000032:analysis* / Q000276:immunology; D002460:Cell Line; D003470:Culture Media / Q000032:analysis; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D007163:Immunosorbent Techniques; D008099:Liver / Q000032:analysis; D011863:Radioimmunoassay / Q000379:methods*; D013205:Staphylococcal Protein A; D013211:Staphylococcus aureus
chemical_list: D003470:Culture Media; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A; D002403:Cathepsins; D002401:Cathepsin B