88090-55-5 Ala-ala-cys-mepda Alanylalanyl-S-(4-(N-(2-thioethyl))aminopyridine-2,6-dicarboxylic acid)cysteine L-Alanine, N-(N-L-alanyl-L-alanyl)-3-((2-((2,6-dicarboxy-4-pyridinyl)amino)ethyl)dithio)-