N-prolylglycine
tert-butyl N-tert-butyloxycarbonyl-L-prolyl-L-phenylalanyl-L-prolylglycyl-L-prolyl-L-isoleucinate
N-tert-butyloxycarbonyl-O-benzyl-L-tyrosyl-L-prolyl-L-phenylalanyl-L-prolylglycine
N-tert-butyloxycarbonyl-L-phenylalanyl-L-prolylglycine
N-benzyloxycarbonyl-L-prolyl-L-isoleucine