1KGG:
reference: Relocation of the catalytic carboxylate group in class A beta-lactamase: the structure and function of the mutant enzyme Glu166-->Gln:Asn170-->Asp., Chen CC, Herzberg O, Protein Eng 1999 Jul;12(7):573-9. PMID: 10436083

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