N-Hydroxysuccinimidyl Iodoacetate

N-Succinimidyl Iodoacetate is a water-insoluble, short-spacer (1.5 Å) crosslinking agent used for selective amine-to-sulfhydryl protein conjugation. It finds applications in protein labeling, antibody conjugation, and protein structure studies. The N-hydroxysuccinimide (NHS) ester reacts with primary amines at slightly basic pH (7–9), while the iodoacetyl group reacts with sulfhydryl groups at pH above 7.5. The resulting amide and thioether bonds are stable and non-cleavable.

In addition to these uses, N-succinimidyl Iodoacetate (SIA) is widely employed in fluorescent and affinity labeling of proteins, preparation of antibody-drug conjugates, and synthesis of peptide-protein bioconjugates with defined stoichiometry. It is also used in the development of diagnostic reagents, such as hapten-carrier conjugates, and in the formation of stable enzyme–antibody or enzyme–protein conjugates for biochemical assays. Its orthogonal reactivity, short spacer arm, and formation of durable linkages make it highly versatile for a broad range of bioconjugation applications.

References:

1. 1. Rector, E. S., Schwenk, R. J., Tse, K. S., & Sehon, A. H. (1978). A method for the preparation of protein-protein conjugates of predetermined composition. Journal of Immunological Methods, 24(3–4), 321–336. https://doi.org/10.1016/0022-1759(78)90135-7