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Structural characterization of metal binding in metallo-b-lactamases using x-ray absorption spectroscopy

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Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/13125

Structural characterization of metal binding in metallo-b-lactamases using x-ray absorption spectroscopy

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Title: Structural characterization of metal binding in metallo-b-lactamases using x-ray absorption spectroscopy
Author: Breece, Robert
Advisor(s): Kirk, Martin
Committee Member(s): Tierney, David
Guo, Hua
Timmins, Graham
Department: University of New Mexico. Dept. of Chemistry
Subject: Metallo-b-lactamase
LC Subject(s): Beta lactamases.
Metalloenzymes.
Binding sites (Biochemistry)
Degree Level: Doctoral
Abstract: In an effort to probe the structure and mechanism of metallo-b-lactamases, the metal-binding behaviors of several enzymes were studied using EXAFS (Extended X-ray Absorption Fine Structure). Three members of the metallo-b-lactamase subclass B1, BcII from Bacillus cereus, Bla2 from Bacillus anthracis and CcrA from Bacillus fragilis, were compared to examine metal-binding behavior within a subclass. Each system exhibits different metal-binding behavior including cooperative binding (BcII), sequential binding (CcrA), and differential binding between zinc(II) and cobalt(II) forms (Bla2). The metal-binding behavior of subclass B3 of L1 from Stenotrophomonas maltophilia was explored with RFQ (rapid-freeze quenched) EXAFS and site selective metal substitution. RFQ EXAFS show the metal coordination at 10 ms in the reaction in the native enzyme including a zinc-zinc distance (3.72Å) greater than is present in either the resting or product-bound states. Metal substitution incorporates cobalt(II) into the Zn2(DHH) of the enzyme and showed the metal-binding at each metal site.
Graduation Date: July 2011
URI: http://hdl.handle.net/1928/13125


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