Quantum Calculations Indicate Effective Electron Transfer between FMN and Benzoquinone in a New Crystal Structure of Escherichia coli WrbA.

Unlabelled: Quantum mechanical calculations using the Marcus equation are applied to compare the electron-transfer probability for two distinct crystal structures of the Escherichia coli protein WrbA, an FMN-dependent

Nad(p)h: quinone oxidoreductase, with the bound substrate benzoquinone. The calculations indicate that the position of benzoquinone in a new structure reported here and solved at 1.33 Å resolution is more likely to be relevant for the physiological reaction of WrbA than a previously reported crystal structure in which benzoquinone is shifted by ∼5 Å.

Molecular dynamics comparison of E. coli WrbA apoprotein and holoprotein.

WrbA is a novel multimeric flavodoxin-like protein of unknown function. A recent high-resolution X-ray crystal structure of E. coli WrbA holoprotein revealed a methionine sulfoxide residue with full occupancy in the FMN-binding site, a finding that was confirmed by mass spectrometry.

1.2 Å resolution crystal structure of Escherichia coli WrbA holoprotein.

The Escherichia coli protein WrbA, an FMN-dependent NAD(P)H:quinone oxidoreductase, was crystallized under new conditions in the presence of FAD or the native cofactor FMN. Slow-growing deep yellow crystals formed with FAD display the tetragonal bipyramidal shape typical for WrbA and diffract to 1.2 Å resolution, the highest yet reported.

Raman spectroscopy adds complementary detail to the high-resolution x-ray crystal structure of photosynthetic PsbP from Spinacia oleracea.

Raman microscopy permits structural analysis of protein crystals in situ in hanging drops, allowing for comparison with Raman measurements in solution. Nevertheless, the two methods sometimes reveal subtle differences in structure that are often ascribed to the water layer surrounding the protein. The novel method of drop-coating deposition Raman spectropscopy (DCDR) exploits an intermediate phase that, although nominally "dry," has been shown to preserve protein structural features present in solution.

Secondary and tertiary structure of nucleotide-binding domain of alphasubunit of Na+/K+-ATPase.

The nucleotide-binding domain of the alpha subunit of mouse brain Na+/K+-ATPase was expressed and isolated from Escherichia coli cells. A model structure was constructed by comparative modeling with and without docked ATP. This was compared with the secondary structure determination from UV circular dichroism and Raman spectroscopy.