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Mechanistic Studies On The Mononuclear ZnIi-Containing Metallo-Β-Lactamase Imis From Aeromonas Sobria, Narayan Sharma, Christine E. Hajdin, Sowmya Chandrasekar, Brian Bennett, Ke-Wu Yang, Michael W. Crowder
Mechanistic Studies On The Mononuclear ZnIi-Containing Metallo-Β-Lactamase Imis From Aeromonas Sobria, Narayan Sharma, Christine E. Hajdin, Sowmya Chandrasekar, Brian Bennett, Ke-Wu Yang, Michael W. Crowder
Physics Faculty Research and Publications
In an effort to understand the reaction mechanism of a B2 metallo-β-lactamase, steady-state and pre-steady-state kinetic and rapid freeze quench electron paramagnetic resonance (EPR) studies were conducted on ImiS and its reaction with imipenem and meropenem. pH dependence studies revealed no inflection points in the pH range of 5.0−8.5, while proton inventories demonstrated at least 1 rate-limiting proton transfer. Site-directed mutagenesis studies revealed that Lys224 plays a catalytic role in ImiS, while the side chain of Asn233 does not play a role in binding or catalysis. Stopped-flow fluorescence studies on ImiS, which monitor changes in tryptophan fluorescence on the enzyme, …
Sequential Binding Of Cobalt(Ii) To Metallo-Β-Lactamase Ccra, Gopal R. Periyannan, Alison L. Costello, David L. Tierney, Ke-Wu Yang, Brian Bennett, Michael W. Crowder
Sequential Binding Of Cobalt(Ii) To Metallo-Β-Lactamase Ccra, Gopal R. Periyannan, Alison L. Costello, David L. Tierney, Ke-Wu Yang, Brian Bennett, Michael W. Crowder
Physics Faculty Research and Publications
In an effort to probe Co(II) binding to metallo-β-lactamase CcrA, EPR, EXAFS, and 1H NMR studies were conducted on CcrA containing 1 equiv (1-Co(II)-CcrA) and 2 equiv (Co(II)Co(II)-CcrA) of Co(II). The EPR spectra of 1-Co(II)-CcrA and Co(II)Co(II)-CcrA are distinct and indicate 5/6-coordinate Co(II) ions. The EPR spectra also reveal the absence of significant spin-exchange coupling between the Co(II) ions in Co(II)Co(II)-CcrA. EXAFS spectra of 1-Co(II)-CcrA suggest 5/6-coordinate Co(II) with two or more histidine ligands. EXAFS spectra of Co(II)Co(II)-CcrA also indicate 5/6 ligands at a similar average distance to 1-Co(II)-CcrA, including an average of about two histidines per Co(II). 1 …