HiLyte Fluor™ 750-IgG conjugate has been optimized in fluorophore/protein labeling ratio to ensure high fluorescent signal and uncompromised IgG function. Spectrally similar to Cy7 dye, HiLyte Fluor™ 750 is the longest-wavelength HiLyte Fluor™ dye currently available. Its fluorescence emission maximum at 778 nm is well separated from commonly used far-red fluorophores such as HiLyte Fluor™ 647, HiLyte Fluor™ 680 or allophycocyanin (APC), facilitating multicolor analysis. With a peak excitation at ~754 nm, conjugates of HiLyte Fluor™ 750 dyes are well excited by a xenon-arc lamp or dye-pumped lasers operating in the 720–750 nm range. The fluorescence signal of HiLyte Fluor™ 750-conjugate can be observed at 778 nm with the excitation at 754 nm.