| Abstract
| - The NMR solution structure of oxidized plastocyanin from the cyanobacterium SynechocystisPCC6803 is here reported. The protein contains paramagnetic copper(II), whose electronic relaxation timesare quite unfavorable for NMR solution studies. The structure has been solved on the basis of 1041 meaningfulNOESY cross-peaks, 18 1D NOEs, 26 T1 values, 96 dihedral angle constraints, and 18 H-bonds. The detectionof broad hyperfine-shifted signals and their full assignment allowed the identification of the copper(II) ligandsand the determination of the Cu−S−C−H dihedral angle for the coordinated cysteine. The global root-mean-square deviation from the mean structure for the solution structure family is 0.72 ± 0.14 and 1.16 ± 0.17 Åfor backbone and heavy atoms, respectively. The structure is overall quite satisfactory and represents abreakthrough, in that it includes paramagnetic copper proteins among the metalloproteins for which solutionstructures can be afforded. The comparison with the available X-ray structure of a triple mutant is also performed.
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