IRDye 680 is ideal for protein/antibody/nucleic acid labeling and other applications where high water solubility is essential.  The NHS ester reactive group provides the functionality for labeling primary and secondary amino groups (e.g. lysines).  IRDye 680 is more tolerant of low pH. 

MW:  950

IRDye 680 Absorbance Spectrum in PBS
IRDye 680 Emission Spectrum in PBS
IRDye 680 in PBS

Absorbance Spectrum | Emission Spectrum | Combination Graph