Kinetic and spectroscopic characterization of native and metal-substituted beta-lactamase from Aeromonas hydrophila AE036.
Two metal ion binding sites are conserved in metallo-beta-lactamase from Aeromonas hydrophila. The ligands of a first zinc ion bound with picomolar dissociation constant were identified by EXAFS spectroscopy as one Cys, two His and one additional N/O donor. Sulfur-to-metal charge transfer bands are observed for all mono- and di-metal species substituted with Cu(II) or Co(II) due to ligation of the single conserved cysteine residue. Binding of a second metal ion results in non-competitive inhibition which might be explained by an alternative kinetic mechanism. A possible partition of metal ions between the two binding sites is discussed.
Hernandez Valladares
M
M
Fachrichtung 12.4 Biochemie, Universität des Saarlandes, D-66041, Saarbrücken, Germany.
Kiefer
M
M
Heinz
U
U
Soto
R P
RP
Meyer-Klaucke
W
W
Nolting
H F
HF
Zeppezauer
M
M
Galleni
M
M
Frère
J M
JM
Rossolini
G M
GM
Amicosante
G
G
Adolph
H W
HW
D016980:Aeromonas hydrophila / Q000201:enzymology* / Q000235:genetics; D001665:Binding Sites; D003035:Cobalt / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D015378:Imipenem / Q000737:chemistry; D007700:Kinetics; D013057:Spectrum Analysis; D015032:Zinc / Q000737:chemistry; D001618:beta-Lactamases / Q000737:chemistry*
D003035:Cobalt; D015378:Imipenem; D003300:Copper; D001618:beta-Lactamases; D015032:Zinc