[Laccase from Coriolus hirsutus--a new marker enzyme for immunoenzyme analysis]

A new immunochemical reagent is proposed which contains laccase, isolated from the culture liquid of the basidial fungus Coriolus hirsutus, as a marker enzyme. The feasibility of immunolaccase conjugates for different variants of immunoassay, i.e. "sandwich", competitive and indirect, is demonstrated. The comparison of immunolaccase and immunoperoxidase conjugates showed that the absolute sensitivity of laccase-antibody conjugates was 3 times higher than that of antibody-peroxidase conjugates (7.7 x 10(-11) M and 2.3 x 10(-10) M, respectively). The assay based on antibody-laccase conjugates is simpler than that employing antibody-peroxidase conjugates, since in the former case air oxygen in used as the second substrate of the enzymatic reaction.