MSD GOLD SULFO-TAG NHS-Ester is an N-hydroxysuccinimide ester which readily couples to primary amine groups of proteins. SULFO-TAG conjugated proteins are used as detection reagents in MSD immunoassays. The conjugates are stable, may be used at low concentrations, have low non-specific binding, and result in highly sensitive detection. The exceptional performance characteristics and simple conjugation procedure of SULFO-TAG NHS-Ester make it the product of choice for molecules that contain primary amines (e.g., lysine in proteins). MSD GOLD SULFO-TAG NHS-Ester has been developed through rigorous multi-lot testing for reproducibility and precision. Exceptional intra-lot and inter-lot consistency of the reagent make it ideal for customers working in validated environments or conducting longitudinal studies that require high performance and reproducibility.