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β-lactamases (EC 220.127.116.11) [1,2] are enzymes which catalyze the hydrolysis
of an amide bond in the β-lactam ring of antibiotics belonging to the
penicillin/cephalosporin family. Four kinds of β-lactamase have been
identified . Class-B enzymes are zinc containing proteins whilst class -A,
C and D enzymes are serine hydrolases. The three classes of serine β-lactamases are evolutionary related and belong to a superfamily  that also
includes DD-peptidases and a variety of other penicillin-binding proteins
(PBP's). All these proteins contain a Ser-x-x-Lys motif, where the serine is
the active site residue. Although clearly homologous, the sequences of the
three classes of serine β-lactamases exhibit a large degree of variability
and only a small number of residues are conserved in addition to the catalytic
Since a pattern detecting all serine β-lactamases would also pick up many
unrelated sequences, we decided to provide specific patterns, centered on the
active site serine, for each of the three classes.
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