The present invention provides modified catalytic
antibody 38C2 with arylation of the reactive
lysine residue (Lys99). The Lys99 residue is arylated with a heteroaryl methyl
sulfonyl compound such as methylsulfone phenyl
oxadiazole (MS-PODA). The invention also provides
antibody conjugated agents (e.g.,
antibody drug conjugates) that contain an agent
moiety that is site-specifically conjugated to 38C2 via a methyl
sulfonyl compound. Further provided in the invention are methods of making the antibody conjugated agents and therapeutic applications of the antibody conjugated agents.