The University of Osaka · Materials Science
Professor Tsuyoshi Inoue's research lab specializes in structural biology and bioinorganic chemistry, focusing on the detailed molecular architecture and electronic properties of blue copper proteins, including nitrite reductases, plastocyanins, and pseudoazurins. The lab employs X-ray crystallography to investigate how subtle changes in copper coordination geometry and protein dynamics influence electron transfer efficiency and protein color. Their work reveals how specific amino acid residues and hydrogen-bonding networks modulate redox activity and protein-protein interactions in microbial respiration and denitrification pathways. The lab's research bridges structural insights with functional mechanisms in metalloenzymes, particularly those involved in nitrogen metabolism and electron transfer in prokaryotes.
Figures are computed from collected data and may differ slightly.
The crystal structure of the blue nitrite reductase from Alcaligenes xylosoxidans GIFU 1051 (AxgNIR) has been determined at 2.05 A resolution. AxgNIR contains both type 1 and 2 Cu sites, the geometry of the former being distorted tetrahedral. The superpositioning of the type 1 Cu sites in the blue enzyme and a green nitrite reductase revealed that the orientation of the Met150 side chain differed. The deviation of the Sdelta(Met150) atom from the axial position of the NNS plane formed by two Nde
The crystal structures of oxidized and reduced plastocyanins from Synechococcus sp. PCC 7942 have been determined at 1.9 and 1.8 A resolution, respectively, at pH 5.0. The protein consists of only 91 amino acid residues, the smallest number known for a plastocyanin, and apparently lacks the mostly conserved acidic patch that is believed to be important for recognition with electron-transfer partners. The protein has two acidic residues, Glu42 and Glu85, around Tyr83, which is thought to be a pos
The crystal structures of oxidized and reduced pseudoazurins from a denitrifying bacterium, Achromobacter cycloclastes IAM1013, have been determined at 1.35- and 1.6-A resolutions, respectively. The copper site in the oxidized state exhibits a distorted tetrahedral structure like those of other pseudoazurins. However, not only a small change of the copper geometry, but concerted peptide bond flips are identified. The imidazole ring of remote His6 has a hydrogen bonding distance of 2.73 A between
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