Using epitope-aequorin conjugate recognition in immunoassays for complex proteins

Recombinant techniques are used to fuse biologically important molecules or peptides to the N-terminus of the photoprotein aequorin such that the bind ing characteristics of the molecule and the bioluminescent activity of aequ orin are retained. This work demonstrates that the peptide region of a bulk y protein can be used to develop an assay for the protein. A heterogeneous competitive binding assay was first developed for HPC4 epitope, the binding region of protein C, using HPC4-apoaequorin conjugate. It was observed tha t the binding of HPC4 epitope to its monoclonal antibody and the biolumines cence properties of aequorin were retained in the fusion protein. The same strategy and the same fusion protein were used to develop the assay for pro tein C. This project could potentially be a model for large biomolecules ut ilizing only the binding region of the protein in the labeled analyte. Also , this assay can be used in clinical diagnostics for the quantitative detec tion of protein C. (C) 2001 Academic Press.