The Active-Site Structure of Umecyanin, the Stellacyanin from Horseradish Roots
- 4 February 2004
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 126 (8), 2481-2489
- https://doi.org/10.1021/ja0375378
Abstract
The type 1 copper sites of cupredoxins typically have a His(2)Cys equatorial ligand set with a weakly interacting axial Met, giving a distorted tetrahedral geometry. Natural variations to this coordination environment are known, and we have utilized paramagnetic (1)H NMR spectroscopy to study the active-site structure of umecyanin (UMC), a stellacyanin with an axial Gln ligand. The assigned spectra of the Cu(II) UMC and its Ni(II) derivative [Ni(II) UMC] demonstrate that this protein has the typical His(2)Cys equatorial coordination observed in other structurally characterized cupredoxins. The NMR spectrum of the Cu(II) protein does not exhibit any paramagnetically shifted resonances from the axial ligand, showing that this residue does not contribute to the singly occupied molecular orbital (SOMO) in Cu(II) UMC. The assigned paramagnetic (1)H NMR spectrum of Ni(II) UMC demonstrates that the axial Gln ligand coordinates in a monodentate fashion via its side-chain amide oxygen atom. The alkaline transition, a feature common to stellacyanins, influences all of the ligating residues but does not alter the coordination mode of the axial Gln ligand in UMC. The structural features which result in Cu(II) UMC possessing a classic type 1 site as compared to the perturbed type 1 center observed for other stellacyanins do not have a significant influence on the paramagnetic (1)H NMR spectra of the Cu(II) or Ni(II) proteins.Keywords
This publication has 33 references indexed in Scilit:
- Metal−Ligand Interplay in Blue Copper Proteins Studied by 1H NMR Spectroscopy: Cu(II)−Pseudoazurin and Cu(II)−RusticyaninJournal of the American Chemical Society, 2002
- Multiple Wavelength Anomalous Diffraction (MAD) Crystal Structure of Rusticyanin: a Highly Oxidizing Cupredoxin with Extreme Acid StabilityJournal of Molecular Biology, 1996
- Crystal structure analysis and refinement at 2·15Å resolution of amicyanin, a type I blue copper protein, from Thiobacillus versutusJournal of Molecular Biology, 1994
- X-ray Analysis and Spectroscopic Characterization of M121Q AzurinJournal of Molecular Biology, 1993
- The amino acid sequence of a type I copper protein with an unusual serine‐ and hydroxyproline‐rich C‐terminal domain isolated from cucumber peelingsFEBS Letters, 1992
- Three-dimensional model for stellacyanin, a “blue” copper-proteinJournal of Molecular Biology, 1991
- Studies on plantacyanin. III. Structural data obtained by CD and MCD methods and antigenic properties of the proteinBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1988
- Structure of azurin from Alcaligenes denitrificans refinement at 1·8 Å resolution and comparison of the two crystallographically independent moleculesJournal of Molecular Biology, 1988
- The crystal structure of pseudoazurin from Alcaligenes faecalis S‐6 determined at 2.9 Å resolutionFEBS Letters, 1987
- The amino acid sequence of stellacyanin from the lacquer treeBiochemical and Biophysical Research Communications, 1977