The present inventors have found that when screening for cyclic peptide compounds that can specifically bind to a target molecule, the use of a library including cyclic peptide compounds having a long side chain in the cyclic portion can improve the hit rate for cyclic peptide compounds that can specifically bind to the target molecule. Meanwhile, the present inventors have found that tryptophan and tyrosine residues, which have conventionally been used in oral low molecular-weight pharmaceuticals and are amino acid residues having an indole skeleton or a hydroxyphenyl group, are not suitable for peptides intended to attain high membrane permeability.
本发明人发现,在筛选能与目标分子特异性结合的环肽化合物时,使用包括环状部分具有长侧链的环肽化合物库,可以提高能与目标分子特异性结合的环肽化合物的命中率。同时,本发明者发现色
氨酸和
酪氨酸残基不适合用于旨在获得高膜渗透性的肽,这两种残基通常用于口服低分子量药物,是具有
吲哚骨架或羟基
苯基的
氨基酸残基。