1 MGK Methyl N-(carboxymethyl)-N-(3-phenylpropyl)glycyl-L-histidinate 1.000 2 MGH Methyl N-(carboxymethyl)-N-(3-phenylpropanoyl)glycyl-D-histidinate 0.967 3 MGJ N-(carboxymethyl)-N-(3-phenylpropyl)glycyl-N-methyl-L-histidinamide 0.871