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 (3.72\xc5) 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.
Level of Degree
Department of Chemistry and Chemical Biology
First Committee Member (Chair)
Second Committee Member
Third Committee Member
Breece, Robert. "Structural characterization of metal binding in metallo-b-lactamases using x-ray absorption spectroscopy." (2011). http://digitalrepository.unm.edu/chem_etds/16