1FQG:
reference: Molecular structure of the acyl-enzyme intermediate in beta-lactam hydrolysis at 1.7 A resolution., Strynadka NC, Adachi H, Jensen SE, Johns K, Sielecki A, Betzel C, Sutoh K, James MN, Nature 1992 Oct 22;359(6397):700-5. PMID: 1436034

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