Question

Since antibodies bind stably and specifically to antigen, they are invaluable as probes for identifying a particular molecule in cells, tissues, or biological fluids. The bound antibody can be visualized with a variety of sensitive techniques, and the specificity of antibody binding coupled to sensitive detection provides remarkable detail about the structure of cells. Immunofluorescence is one of these techniques. What is a widely used fluorescent compound that can be easily coupled to free amino acid groups on antibodies that fluoresces red?

Fluorescein isothiocyanate
Phycoerythrin
Immunophilin
Phytohemagglutinin
Protein A

Answer 1

Phycoerythrin is the fluorescent compound that fluoresces red when coupled to antibodies, and is used in immunofluorescence assays for sensitive detection of antigens.

Step-by-step explanation:

In immunofluorescence, antibodies are used to detect antigens with high specificity. To visualize antigen-antibody interactions, these antibodies are often tagged with fluorescent compounds. A widely used fluorescent compound that fluoresces red when coupled to free amino acid groups on antibodies is phycoerythrin. Unlike fluorescein isothiocyanate, which fluoresces green, phycoerythrin provides a distinct red fluorescence, making it valuable in applications such as flow cytometry where multiple fluorophores may be used concurrently to label different targets within a cell or a complex mixture of cells.