1iuz
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PLASTOCYANIN
OverviewOverview
The crystal structure of plastocyanin from a green alga, Ulva pertusa, has, been determined at 1.6-A resolution. At its copper site, U. pertusa, plastocyanin has a distorted tetrahedral coordination geometry similar to, other plastocyanins. In comparison with structures of plastocyanins, reported formerly, a Cu(II)-Sdelta(Met92) bond distance (2.69 A) is, shorter by about 0.2 A and a Cu(II)-Sgamma(Cys84) distance is longer by, less than 0.1 A in U. pertusa plastocyanin. These subtle but significant, differences are caused by the structural change at a His-Met loop, (His87-Met92) due to an absence of a O(Asp85)-Ogamma(Ser88) hydrogen bond, which is found in Enteromorpha prolifera plastocyanin. In addition, poplar, and Chlamydomonas reinhardtii plastocyanins with a glutamine at residue 88, have a weak cation-pi interaction with Tyr83. This interaction lengthens, the Cu(II)-Sdelta(Met92) bond of poplar and C. reinhardtii plastocyanins, by 0.14 and 0.20 A, respectively. As a result of structural differences, U. pertusa plastocyanin has a less distorted geometry than the other, plastocyanins. Thus, the cupric geometry is finely tuned by the, interactions between residues 85 and 88 and between residues 83 and 88., This result implies that the copper site is more flexible than reported, formerly and that the rack mechanism would be preferable to the entatic, theory. The His-Met loop may regulate the electron transfer rate within, the complex between plastocyanin and cytochrome f.
About this StructureAbout this Structure
1IUZ is a Single protein structure of sequence from Ulva pertusa with and as ligands. Known structural/functional Site: . Full crystallographic information is available from OCA.
ReferenceReference
Novel insight into the copper-ligand geometry in the crystal structure of Ulva pertusa plastocyanin at 1.6-A resolution. Structural basis for regulation of the copper site by residue 88., Shibata N, Inoue T, Nagano C, Nishio N, Kohzuma T, Onodera K, Yoshizaki F, Sugimura Y, Kai Y, J Biol Chem. 1999 Feb 12;274(7):4225-30. PMID:9933621
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