RB 101 [ RB101,N-(2-benzyl-3-((2-amino-4-methylthio)butyl dithio)-1-oxopropyl)phenylalanine benzyl ester,RB-101 ] structure given in first source; inhibits enkephalinase and aminopeptidases; biologically cleaved at disulfide to produce inhibitors of both aminopeptidase N and neutral endopeptidase