INVESTIGADORES
RASIA Rodolfo Maximiliano
artículos
Título:
Structural determinants of substrate binding to Bacillus cereus metallo-beta-lactamase
Autor/es:
RASIA RM; VILA AJ
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Referencias:
Año: 2004 vol. 279 p. 26046 - 26051
ISSN:
0021-9258
Resumen:
Binding and hydrolysis of the beta-lactams
cefotaxime, cephapirin, imipenem, and benzylpenicillin by the
metallo-beta-lactamase from Bacillus cereus were studied by presteady
state kinetic measurements. In all cases, the substrate was unmodified
in the most populated reaction intermediate, and no chemically modified
substrate species accumulated to a detectable amount. The
cephalosporins tested showed similar formation rate constants for this
intermediate, and they differed mostly in their decay rates. Formation
of a non-productive enzyme . substrate complex was detected for
imipenem. The substrate binding differences can be accounted for by
considering the structural features of each substrate. The apoenzyme
could not bind any of the substrates, but binding was restored when the
apoenzyme was reconstituted with Zn(II), revealing that the metal ions
are the main determinants of substrate binding. This evidence is in
line with the lack of an optimized substrate recognition patch in B1
and B3 metallo-beta-lactamases that provides a broad substrate spectrum.
Document Type: Article