What are the advantages of allophycocyanin (APC)?

Question

Accepted Answer

Allophycocyanin (APC) is a 105 kDa phycobiliprotein found in cyanobacteria and red algae. It exhibits a bright far-red fluorescence with a molar extinction coefficient of 700,000 cm-1M-1 and a fluorescence quantum yield of 0.68. The fluorescence spectral of APC in its native state is characterized by two absorbance peaks, a primary absorbance peak at 651 nm and a secondary absorbance peak at 625 nm, and a single emission maximum at 660 nm. This dual absorbance maxima improves compatibility with imaging instruments equipped with red lasers (633-647 nm). Just like PE, APC must first be conjugated to a molecule having biological specificity, such as an antibody, streptavidin or annexin V prior to using. It offers several advantages that make it a popular choice for multicolor flow cytometry experiments:

Long-wavelength emission profiles minimizes autofluorescence from biological materials
Minimal fluorescence quenching contributed by the covalent binding of phycobilins to the protein backbone
Very high water-solubility to facilitate chemical manipulation for conjugation reactions
Significant Stokes shifts with resolvable emission spectra for multicolor analysis
Multiple sites for stable conjugation with organic and synthetic compounds such as antibodies, cyanine dyes or iFluor® dyes
Tandem conjugates for multicolor flow cytometry - generate a range of emission signals with a single excitation laser

Related questions