INVESTIGADORES
RASIA Rodolfo Maximiliano
artículos
Título:
Mechanistic study of the hydrolysis of nitrocefin mediated by B.cereus metallo-beta-lactamase
Autor/es:
RASIA RM; VILA AJ
Revista:
Arkivoc
Referencias:
Año: 2003 vol. 2003 p. 507 - 516
ISSN:
1424-6376
Resumen:
The hydrolysis of the beta-lactam compound nitrocefin by the
metallo-beta-lactamase from B. cereus (BcII) was studied by pre-steady
state kinetics measurements, followed by absorbance, fluorescence and
diode array detection. In contrast with the results reported for the
homologous enzymes CcrA from B. fragilis and L1 from S. maltophilia, no
accumulation of an anionic intermediate could be evidenced. The
rationale for this observation can be tracked on the lower binding
affinity toward a second Zn(II) ion in this enzyme, and the
modification of a flexible active site loop, that might contribute to
stabilize the anionic intermediate. Analysis of the substrate binding
and product formation rates does not support a recently proposed
mechanistic scheme that contemplates a non-negligible accumulation of
this intermediate in nitrocefin hydrolysis by BcII.