Iron(III) Located in the Dinuclear Metallo-beta-Lactamase IMP-1 by Pseudocontact Shifts.
Carruthers, T.J., Carr, P.D., Loh, C.T., Jackson, C.J., Otting, G.(2014) Angew Chem Int Ed Engl 53: 14269-14272
- PubMed: 25320022 
- DOI: https://doi.org/10.1002/anie.201408693
- Primary Citation of Related Structures:  
4UAM - PubMed 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 Fe(3+), 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 Fe(3+).
Organizational Affiliation: 
Research School of Chemistry, Australian National University, Canberra, ACT 0200 (Australia).