1IYO:
reference: Acyl-intermediate structures of the extended-spectrum class A beta-lactamase, Toho-1, in complex with cefotaxime, cephalothin, and benzylpenicillin., Shimamura T, Ibuka A, Fushinobu S, Wakagi T, Ishiguro M, Ishii Y, Matsuzawa H, J Biol Chem 2002 Nov 29;277(48):46601-8. Epub 2002 Sep 8. PMID: 12221102

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