Allophycocyanin (APC) conjugates are used in FRET screening, flow cytometry, immunoassays and MHC tetramer assays. APC is a highly absorptive fluorescent molecule that has excellent detectability. APC is usually used in an internally crosslinked form (Crosslinked APC) which is stable at the low concentrations required for most uses. Conventional conjugation techniques will not alter the spectral characteristics of this product. Using our highly purified Crosslinked APC, we manufacture a variety of APC conjugates for different applications. We also offer SMCC-activated APC for simplified conjugation to antibodies and other sulfhydryl-containing proteins of interest. Custom conjugations to APC are also available.