Description
Enzymes are widely used in bioconjugate chemistry as detection components in assay systems. The catalytic activity of an enzyme can be used to turn substrate molecules into chro- mogenic, fluorescent, or chemiluminescent products, which are easily detectable or quantifiable by imaging, microscopy, or spectroscopy. If an enzyme is conjugated to a targeting molecule specific for some analyte of interest, then an assay system can be constructed to localize or measure the analyte. The most common targeting molecule is an antibody having antigen-binding specificity for the substance to be measured. An enzyme conjugated to such an anti-body can be used to visualize the presence of antigen. Due to the advantages of this simple concept, enzyme linked immunoadsorbent assays (ELISAs) have become the most important type of immunoassay system available. Besides, the flexibility of enzyme-based assay systems makes the chemistry of enzyme conjugation one of the most important application areas in bioconjugate techniques.