90991-75-6 Cpe-ala-ala-phe-pab Cpp-ala-ala-phe-pab L-Phenylalaninamide, N-(1-carboxy-2-phenylethyl)-L-alanyl-L-alanyl-N-(4-carboxyphenyl)- N-(1-Carboxy-2-phenylethyl)-alanyl-alanyl-phenylalanine-4-aminobenzoate