Compounds are provided termed "betides" which mimic peptides and which contain one or more residues of aminoglycine, C.sup..alpha. -aminoalanine, aminosarcosine or the like wherein the side chain amino group has been acylated and optionally also alkylated. Generally, betides have the formula: X.sub.N --X.sub.1 --X.sub.2 --X.sub.3 --X.sub.m --X.sub.4 --X.sub.5 --X.sub.6 --X.sub.C, where X.sub.N is an acyl or other N-terminal group or a peptide up to about 50 amino acids in length having such a group; X.sub.C is OH, NH.sub.2 or other C-terminal group or a peptide up to about 50 amino acids in length having such a group; and X.sub.1 -X.sub.6 are each independently a betide amino acid or .alpha.-amino acid or des-X; and X.sub.m is a peptide up to about 50 amino acids or des-X; provided however that at least one of X.sub.1 -X.sub.6 is a betide amino acid residue having the formula: ##STR1## wherein R.sub.o is H or CH.sub.3, R and R.sub.2 are H or lower alkyl, and R.sub.3 is an acyl group, an isocyanate group, an isothiocyanate group or a sulfonyl group. In methods for making betides, an aminoglycine residue can be subjected to side chain acylation, and optionally also alkylation, after it has been incorporated into a peptide intermediate. This method can be used as a valuable tool to synthesize and screen multiple substituents at one or more positions in a peptide, permitting simultaneous screening of betides which mimic peptides having a large number of natural or unnatural amino acid substituents at a particular position, and optionally both D- and L-isomers of those substituents.