1kdi

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spinqualitylabelsall models 1kdi, resolution 1.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

REDUCED FORM OF PLASTOCYANIN FROM DRYOPTERIS CRASSIRHIZOMA

Overview

Spectroscopic properties, amino acid sequence, electron transfer kinetics, and crystal structures of the oxidized (at 1.7 A resolution) and reduced, form (at 1.8 A resolution) of a novel plastocyanin from the fern, Dryopteris crassirhizoma are presented. Kinetic studies show that the, reduced form of Dryopteris plastocyanin remains redox-active at low pH, under conditions where the oxidation of the reduced form of other, plastocyanins is inhibited by the protonation of a solvent-exposed active, site residue, His87 (equivalent to His90 in Dryopteris plastocyanin). The, x-ray crystal structure analysis of Dryopteris plastocyanin reveals pi-pi, stacking between Phe12 and His90, suggesting that the active site is, uniquely protected against inactivation. Like higher plant plastocyanins, Dryopteris plastocyanin has an acidic patch, but this patch is located, closer to the solvent-exposed active site His residue, and the total, number of acidic residues is smaller. In the reactions of Dryopteris, plastocyanin with inorganic redox reagents, the acidic patch (the "remote", site) and the hydrophobic patch surrounding His90 (the "adjacent" site), are equally efficient for electron transfer. These results indicate the, significance of the lack of protonation at the active site of Dryopteris, plastocyanin, the equivalence of the two electron transfer sites in this, protein, and a possibility of obtaining a novel insight into the, photosynthetic electron transfer system of the first vascular plant fern, including its molecular evolutionary aspects. This is the first report on, the characterization of plastocyanin and the first three-dimensional, protein structure from fern plant.

About this Structure

1KDI is a Single protein structure of sequence from Eukaryota with CU as ligand. Full crystallographic information is available from OCA.

Reference

The structure and unusual pH dependence of plastocyanin from the fern Dryopteris crassirhizoma. The protonation of an active site histidine is hindered by pi-pi interactions., Kohzuma T, Inoue T, Yoshizaki F, Sasakawa Y, Onodera K, Nagatomo S, Kitagawa T, Uzawa S, Isobe Y, Sugimura Y, Gotowda M, Kai Y, J Biol Chem. 1999 Apr 23;274(17):11817-23. PMID:10206999

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