Iron(III) Located in the Dinuclear Metallo‐β‐Lactamase IMP‐1 by Pseudocontact Shifts |
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| Authors: | Thomas J. Carruthers Dr. Paul D. Carr Dr. Choy‐Theng Loh Dr. Colin J. Jackson Prof. Gottfried Otting |
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| Affiliation: | Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia) |
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| Abstract: | Heterodinuclear metalloenzymes are an important class of metalloproteins, but determining the location of the different metal ions can be difficult. Herein we present a new NMR spectroscopy method that uses pseudocontact shifts (PCS) to achieve this without assumptions about the coordinating ligands. The approach is illustrated with the dinuclear [FeZn] complex of IMP‐1, which is a prototypical metallo‐β‐lactamase (MβL) that confers resistance to β‐lactam antibiotics. Results from single‐crystal X‐ray diffraction were compromised by degradation during crystallization. With [GaZn]‐IMP‐1 as diamagnetic reference, the PCSs unambiguously identified the iron binding site in fresh samples of [FeZn]‐IMP‐1, even though the two metal centers are less than 3.8 Å apart and the iron is high‐spin Fe3+, which produces only small PCSs. [FeZn]‐MβLs may be important drug targets, as [FeZn]‐IMP‐1 is enzymatically active and readily produced in the presence of small amounts of Fe3+. |
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| Keywords: | dinuclear metalloenzymes IMP‐1 metallo‐β ‐lactamase NMR spectroscopy pseudocontact shifts |
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