Methods of making and screening betide libraries

Abstract

Compounds termed 'betides' mimic peptides and 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 betidamino 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 betidamino acid residue having the formula: ##STR1## wherein R.sub.0 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 or isothiocyanate group, a sulfonyl group or the like. To make a betide, an aminoglycine residue is subjected to side chain acylation, and optionally also alkylation, after it is coupled into a peptide intermediate. By synthesizing betides with multiple substituents at one or more positions in an otherwise peptidic chain, efficient screening of betides which mimic peptides having a large number of different natural or unnatural amino acid substituents at a particular position, and optionally both D- and L-isomers thereof, is possible.