Iodoacetyl Agarose Resin

Iodoacetyl agarose resin is a pre-activated chromatography support used for the covalent, thiol-directed immobilization of sulfhydryl-containing molecules such as proteins, peptides, and antibody fragments. The resin consists of cross-linked agarose beads functionalized with iodoacetyl groups, typically at the end of a spacer arm. The iodoacetyl group reacts specifically with free sulfhydryl (–SH) groups—the side chains of reduced cysteine residues—via nucleophilic substitution, in which the thiol displaces the iodide to form a stable, irreversible thioether bond. Iodoacetyl agarose resin is particularly useful for oriented immobilization. Because many proteins and peptides have only one or a few cysteine residues (or can be engineered to include a single terminal cysteine), the ligand can be attached at a defined site, leaving its functional or binding regions free and properly oriented—an advantage over amine-based coupling, which attaches randomly through the many lysines on a protein. It is also the method of choice for immobilizing cysteine-containing peptides, reduced antibody fragments (e.g., Fab’ via hinge thiols), and other thiol-containing ligands. BiCell Scientific’s Iodoacetyl affinity resin uses 4% highly cross-linked agarose matrix with a mean size of 90 μm and capable of operating under 0.1 MPa (1 bar/14.5 psi). The hydrophilic nature of the matrix ensures low levels of non-specific binding leading to low levels of host cell-derived impurities in the elution pool. The coupling capacity for iodoacetyl resin is expressed as the amount of thiol-containing ligand it can immobilize, which falls ~8-15 µmol of cysteine-containing peptide per mL of resin.