heterodetic cyclic peptide

https://doi.org/10.1351/goldbook.H02800
A peptide consisting only of amino-acid residues, but in which the linkages forming the ring are not solely eupeptide bonds; one or more is an isopeptide, disulfide, ester, or other bond.
Source:
White Book, 2nd ed., p. 59 (https://www.qmul.ac.uk/sbcs/iupac/bibliog/white.html)