4GUX:
reference: Structural insights into the role of the cyclic backbone in a squash trypsin inhibitor., Daly NL, Thorstholm L, Greenwood KP, King GJ, Rosengren KJ, Heras B, Martin JL, Craik DJ, J Biol Chem. 2013 Dec 13;288(50):36141-8. doi: 10.1074/jbc.M113.528240. Epub 2013, Oct 29. PMID: 24169696

This OCA Structure page
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