Thiol Reactive Linkers are used in ADC conjugation to target thiol group on biomolecules. Maleimide, acrylamide, vinyl sulfone, bromide and tosylated linkers are some of the most useful thiol reactive agents for bioconjugation. The maleimide linkers allow selective labeling of sulfhydryl groups such as cysteine residues in proteins and pepties, and oligonucleotides. Functionalized maleimide linkers with PEG spacer of different length offers researchers flexibility to fine tune their conjugation applications.
Besides amine-reactive compounds, thiol or sulfhydryls (–SH) reactive linkers are the most common crosslinkers for protein and other bioconjugations. Thiols exist in proteins’ side-chain of cysteine (Cys, C) amino acids. They often exist as disulfide bonds (–S–S–) within or between polypeptide chains as the basis of native tertiary or quaternary protein structure. Only the free or reduced sulfhydryl groups (–SH) are available for reaction with thiol-reactive compounds.