SIAB is an amine- and sulfhydryl-reactive heterobifunctional crosslinker and Sulfo-SIAB is its water-soluble analog. These crosslinkers contain an amine-reactive N-hydroxysuccimide (NHS) ester and a sulfhydryl-reactive iodoacetyl group, and are often used for preparing enzyme conjugates or immunotoxins. Water-soluble and water-insoluble forms of NHS esters have essentially identical reactivity. Sulfo-SIAB is supplied as a sodium salt and is water-soluble to ~10mM. SIAB must be first dissolved in an organic solvent, such as DMSO or DMF, and then added to the aqueous reaction mixture. SIAB is lipophilic, membrane-permeable and does not possess a charged group.
