Micro-method for the Estimation of Specific Proteins in Mixtures

Abstract

THE method described here is a, micro-version of one developed earlier¹ and is based on the gel-diffusion technique of Ouchterlony². It is suitable for any protein or other macromolecule which can diffuse through a weak agar gel and for which precipitating antibodies are obtainable. Its advantages over the macro-method are that it requires only a small volume of reagents (about 0.12 ml. of dilute protein and 0.03 ml. of dilute antibody solution), that the incubation period is 18 h or less, that the use of quantitative micro-pipettes is unnecessary, and that it can be carried out on microscope slides instead of Petri dishes. Its error of estimation when tested on a glycoprotein of rat serum was ± 8 per cent (95 per cent confidence limits) compared with ± 5 per cent for the macro-method. It has also been found satisfactory for titration of a mouse serum myeloma globulin³.