Molecular structure of the acyl-enzyme intermediate in beta-lactam hydrolysis at 1.7 A resolution

Nature. 1992 Oct 22;359(6397):700-5. doi: 10.1038/359700a0.


The X-ray crystal structure of the molecular complex of penicillin G with a deacylation-defective mutant of the RTEM-1 beta-lactamase from Escherichia coli shows how these antibiotics are recognized and destroyed. Penicillin G is covalently bound to Ser 70 0 gamma as an acyl-enzyme intermediate. The deduced catalytic mechanism uses Ser 70 0 gamma as the attacking nucleophile during acylation. Lys 73 N zeta acts as a general base in abstracting a proton from Ser 70 and transferring it to the thiazolidine ring nitrogen atom via Ser 130 0 gamma. Deacylation is accomplished by nucleophilic attack on the penicilloyl carbonyl carbon by a water molecule assisted by the general base, Glu 166.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acylation
  • Amino Acid Sequence
  • Binding Sites
  • Catalysis
  • Crystallography
  • Escherichia coli / enzymology
  • Hydrogen Bonding
  • Models, Molecular
  • Molecular Sequence Data
  • Penicillin G* / chemistry
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Serine / chemistry
  • Structure-Activity Relationship
  • X-Ray Diffraction
  • beta-Lactamases / chemistry
  • beta-Lactamases / ultrastructure*


  • Serine
  • beta-Lactamases
  • Penicillin G