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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 …}