Method for producing peptides having azole-derived skeleton

A method of constructing a peptide library having, in the backbone thereof, an azole derivative structure, comprising the steps of:

• constructing an mRNA library encoding a substrate peptide library including two or more substrate peptides of an azoline structure introducing enzyme different in sequence of a modified region, the substrate peptides each containing, in the modified region thereof, at least any one of the following amino acids:
• wherein
• X1 represents a group selected from the group consisting of SH, OH, NH2, SR1, OR1, NHR1, and N3, wherein R1 represents a protecting group,
• X2 represents an easily eliminable group;
• and
• X3 represents hydrogen or a substituted or unsubstituted alkyl or aryl group having from 1 to 10 carbon atoms;
• translating the mRNA library in a cell-free translation system to obtain a substrate peptide library;
• reacting the substrate peptide library with an azoline structure introducing enzyme to obtain a peptide library having an azoline derivative structure;
• and
• obtaining a peptide library having an azole derivative structure by inducing an elimination reaction of X2 group and thereby converting the azoline derivative structure of the peptide library having an azoline derivative structure into an azole derivative structure.