Peptide Aptamer-Based ELISA-Like System for Detection of Cathepsin E in Tissues and Plasma

ELISA (enzyme-linked immunosorbent assay), a highly sensitive and powerful molecular detection tool, has been constructed based on antibodies, as its name denotes. However, it is not so easy to prepare antibodies for any target molecule and there are still problems in their cost and stability. In this study, peptide-based ELISA-like systems (pep- ELISA) were first constructed and shown to be effective. In particular, if the target is an enzyme, such as cathepsin E, that can generate a fluorescent product, the construct of pep-ELISA can be very simple, as its name indicates; i.e., Enzyme-on-Peptide. These constructs, together with peptide-based Sandwich ELISA-like (Sandwich pep-ELISA), were actually constructed and examined using the tissues and blood specimens extracted from cathepsin E-normal/knockout rats. Through these experiments, the sufficient sensitivity (~10µg/ml) and methodological convenience of pep-ELISA were demonstrated.