Comparison of an Enzyme Immunoassay Versus Mass Spectrometry-based Assay for the Quantitative Determination of the Procollagen Type I N-terminal Propeptide in Rat Serum

Traditionally, antibody-based assays, such as enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA), are the primary tool for the targeted quantification of a specific protein. An antibody-based assay can be run at high-throughput and has extraordinary sensitivity and specificity. In the cases where antibody-based assays exist, the process of validating biomarker candidates can be relatively straightforward. However, the antibody-based approach is limited by the lack of availability of antibodies with high specificity. The development of a high quality antibody-based assays can be costly, time-consuming and a resource-intensive effort. Another disadvantage of antibody-based assays is that they often do not discriminate closely related isoforms. While the antibody development is central to the success of antibody-based platform, mass spectrometry (MS) provides alternative and complementary approach to existing antibody-based assays. The MS-based assays are becoming very popular for quantitative candidates proteins detection in a complex biological mixture. In the present paper, an in-house developed mass spectrometry (MS)-based assay was compared to a commercially available EIA in reproducibility, measurement accuracy, and dynamic range using rat procollagen type-I N-terminal propeptide (P1NP) as a model.