4-Mercaptophenylacetic acid (MPAA), a thiol additive, is widely used in Native Chemical Ligation (NCL) reactions for selective and efficient ligation of peptide fragments.
M 1115 (OTTO) 4-Mercaptophenylacetic acid, 97% Cas 39161-84-7 - used in the preparation of small ubiquitin-like modifier peptides from bis(2-sulfanylethyl)amido peptide via sequential native chemical ligation.