title: Identification of the active site of Citrobacter freundii beta-lactamase using dansyl-penicillin.
abstract: The active site sequence of a beta-lactamase encoded by chromosomal gene(s) in Citrobacter freundii GN346 was determined using dansyl-penicillin as a fluorescent probe. The tryptic digest of the labelled enzyme gave a fluorescent peptide containing 22 amino acids. The sequence of this peptide was identical to the consensus sequence of class C beta-lactamases, Gly-Ser-X-Ser-Lys. The residue labelled was the serine adjacent to the glycine. The active site sequence corresponded to positions 46-67 of the entire sequence of the Citrobacter freundii beta-lactamase determined on the basis of the DNA sequence of the structural gene [(1986) Eur. J. Biochem. 156, 441-445]. The labelled serine corresponded to Ser-64.
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D002510:Cephalosporinase / Q000378:metabolism*; D002954:Citrobacter / Q000201:enzymology*; D003619:Dansyl Compounds / Q000378:metabolism; D010406:Penicillins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003619:Dansyl Compounds; D010406:Penicillins; D010446:Peptide Fragments; D002510:Cephalosporinase; D001618:beta-Lactamases