1DSM:
reference: The structural basis for in situ activation of DNA alkylation by duocarmycin SA., Smith JA, Bifulco G, Case DA, Boger DL, Gomez-Paloma L, Chazin WJ, J Mol Biol. 2000 Jul 28;300(5):1195-204. PMID: 10903864

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