SIA is a heterobifunctional amine to sulfhydryl crosslinking reagent.SIA contains one NHS ester group and a iodoacetyl reactive group at each end of a short 1.5 angstroms spacer.The NHS ester groups readily react towards primary amines at pH 7-9.The iodoacetyl group reacts towards sulfhydryl (or thiol) groups at pH > 7.5.SIA is not water soluble and must be dissolved in an organic solvent such as DMSO or DMF prior to use.