SULFO-TAG NHS Ester

This protocol details the labeling procedure for proteins of molecular weight (MW) > 40000 Daltons using MSD® SULF0-

TAG NHS Ester. The straightforward procedure involves a buffer exchange (if necessary), an incubation step for 2 hours,

and the use of a spin column to quickly isolate the labeled protein. MSD SULFO-TAG NHS-Ester (Figure 1) is an aminereactive,

N-hydroxysuccinimide ester which readily couples to primary amine groups of proteins under mildly basic conditions

to form a stable amide bond.

MSD SULFO-TAG™conjugates are stable and may be used at low concentrations. These features minimize time, cost, and

labor as large batches of a stable conjugate can be prepared, validated, and used for long periods of time. Its excellent performance

characteristics and simple labeling procedure make MSD SULFO-TAG NHS-Ester the product of choice for molecules

that contain primary amines (e.g. lysine-containing proteins). MSD SULFO-TAG offers low non-specific binding, resulting

in highly sensitive detection when used in conjunction with MSD's SECTOR® instruments and SECTOR PR® readers.