PACMA 31 is an irreversible, orally active protein disulfide isomerase (PDI) inhibitor with an IC50 of 10 μM. PACMA 31 forms a covalent bond with the active site cysteines of PDI. PACMA 31 shows tumor targeting ability and significantly suppresses ovarian tumor growth without causing toxicity to normal tissues[1]. PACMA 31 is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.