Abstract
Structurally identifying the enzymatic intermediates of redox proteins has been elusive due to difficulty in resolving the H atoms involved in catalysis and the susceptibility of ligand complexes to photoreduction from X-rays. Cryotrapping ligands for neutron protein crystallography combines two powerful tools that offer the advantage of directly identifying hydrogen positions in redox-enzyme intermediates without radiolytic perturbation of metal-containing active sites. However, translating cryogenic techniques from X-ray to neutron crystallography is not straightforward due to the large crystal volumes and long data-collection times. Here, methods have been developed to visualize the evasive peroxo complex of manganese superoxide dismutase (MnSOD) so that all atoms, including H atoms, could be visualized. The subsequent cryocooling and ligand-trapping methods resulted in neutron data collection to 2.30 Å resolution. The P6122 crystal form of MnSOD is challenging because it has some of the largest unit-cell dimensions (a = b = 77.8, c = 236.8 Å) ever studied using high-resolution cryo-neutron crystallography. The resulting neutron diffraction data permitted the visualization of a dioxygen species bound to the MnSOD active-site metal that was indicative of successful cryotrapping.
Original language | English (US) |
---|---|
Pages (from-to) | 8-16 |
Number of pages | 9 |
Journal | Acta Crystallographica Section F: Structural Biology Communications |
Volume | 78 |
DOIs | |
State | Published - Jan 1 2022 |
Keywords
- Cryotrapping
- Human manganese superoxide dismutase
- Large unit cell
- Neutron diffraction
- Peroxide
ASJC Scopus subject areas
- Biophysics
- Structural Biology
- Biochemistry
- Genetics
- Condensed Matter Physics