6FCE:
reference: Development of Macrocyclic Peptidomimetics Containing Constrained alpha,alpha-Dialkylated Amino Acids with Potent and Selective Activity at Human Melanocortin Receptors., Merlino F, Zhou Y, Cai M, Carotenuto A, Yousif AM, Brancaccio D, Di Maro S, Zappavigna S, Limatola A, Novellino E, Grieco P, Hruby VJ, J Med Chem. 2018 Apr 16. doi: 10.1021/acs.jmedchem.8b00488. PMID: 29660981

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).