title: [Radiocompetitive assay of sulfamido-3-chloro-4-benzoic acid with carbonic anhydrase as binding reagent (author's transl)].
abstract: The control of patients treated by diuretic sulfonamides can be carried out by a radiocompetitive assay using their binding properties to carbonic anhydrase (CA). In this paper we have studied the assay of sulfamido-3-chloro-4-benzoic acid (SD3) using dialysis equilibrium as separation procedure. With (CA) 2 X 10(-6) M and 14C-SD3 0.5 X 10(-6) M (specific activity: 2 muCi/mg), can be detected 0.5 X 10(-6) M of (SD3) in the assay medium. 6.5 mg protein present in serum lower the assay sensitivity twenty times, owing to an elevated value of the affinity constant, Ka, of albumin-(SD3) complex (10(3) mol-1). On the other hand, the molecules with sulfamidobenzoic group cannot be differentiated in this procedure.
mesh_terms: D001665:Binding Sites / Q000187:drug effects; D001667:Binding, Competitive; D001798:Blood Proteins; D002256:Carbonic Anhydrases; D055598:Chemical Phenomena; D002621:Chemistry; D002723:Chlorobenzoates / Q000032:analysis*; D004232:Diuretics / Q000032:analysis*; D006801:Humans; D007700:Kinetics; D011485:Protein Binding; D012710:Serum Albumin, Bovine; D013449:Sulfonamides
chemical_list: D001798:Blood Proteins; D002723:Chlorobenzoates; D004232:Diuretics; D013449:Sulfonamides; D012710:Serum Albumin, Bovine; D002256:Carbonic Anhydrases
vernacular_title: Dosage d'un sulfamide diurétique, l'Acide sulfamido-3-chloro-4-benzoique, par radiocompetition avec l'anhydrase carbonique.