5KX5:
reference: Design, Synthesis, and Cytotoxic Evaluation of Novel Tubulysin Analogues as ADC Payloads., Leverett CA, Sukuru SC, Vetelino BC, Musto S, Parris K, Pandit J, Loganzo F, Varghese AH, Bai G, Liu B, Liu D, Hudson S, Doppalapudi VR, Stock J, O'Donnell CJ, Subramanyam C, ACS Med Chem Lett. 2016 Aug 26;7(11):999-1004. eCollection 2016 Nov 10. PMID: 27882198

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