Acetamidomethyl. The sulfhydryl protecting group Acm is compatible with Fmoc and Boc chemistry. Acm is cleaved by Hg(II) or Ag(I) or by iodine with concomitant oxidation. When synthesizing peptides containing two disulfide bridges via consecutive S-S- bond formation, Acm is often chosen in combination with acid-labile thiol protection.