Final answer:
In a fluorescent enzyme immunoassay (FEIA), the fluorogen replaces the substrate that is usually used in an EIA, aiding in the detection of fluorescence instead of a color change for a more specific reading.
Step-by-step explanation:
When performing a fluorescent enzyme immunoassay (FEIA), the fluorogen replaces the enzyme substrate that is used in an enzyme immunoassay (EIA). In EIAs, a chromogen or a fluorogen can be used as substrates for the enzyme. The substrate is a colorless molecule that the enzyme converts into a colored end product or into a fluorescent form. Typically, the most widely used enzymes in such assays are alkaline phosphatase and horseradish peroxidase.
In FEIAs, the detection is based on the measurement of fluorescence rather than color change, which allows for a more sensitive and specific reading. Blockquote>