Peroxidase Labelling of Antibodies for Use in Enzyme Immunoassay

Methods for labelling IgG with horseradish peroxidase using glutaraldehyde (one step and two step methods) and periodate oxidation are compared. The conjugate prepared by the periodate-oxidation gives a much steeper dose-response curve in the immunoassay than the other conjugates. The yields of enzyme activity and immunoactivity are low. The perioxidate oxidation method does not seem to be sufficiently reproducible. The conjugate was the most efficient when tested in an enzyme immunoassay. Its large size (molecular weight about 106) may be a disadvantage in some applications. In these cases conjugates prepared by the two-step glutaraldehyde method would be the most appropriate (mol.weight 2-4-105). (Heyrovsky - Prague - CSSR)