1jer
CUCUMBER STELLACYANIN, CU2+, PH 7.0
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OverviewOverview
Stellacyanins are blue (type I) copper glycoproteins that differ from, other members of the cupredoxin family in their spectroscopic and electron, transfer properties. Until now, stellacyanins have eluded structure, determination. Here we report the three-dimensional crystal structure of, the 109 amino acid, non-glycosylated copper binding domain of recombinant, cucumber stellacyanin refined to 1.6 A resolution. The crystallographic, R-value for all 18,488 reflections (sigma > 0) between 50-1.6 A is 0.195., The overall fold is organized in two beta-sheets, both with four, beta-stands. Two alpha-helices are found in loop regions between, beta-strands. The beta-sheets form a beta-sandwich similar to those found, in other cupredoxins, but some features differ from proteins such as, plastocyanin and azurin in that the beta-barrel is more flattened, there, is an extra N-terminal alpha-helix, and the copper binding site is much, more solvent accessible. The presence of a disulfide bond at the copper, binding end of the protein confirms that cucumber stellacyanin has a, phytocyanin-like fold. The ligands to copper are two histidines, one, cysteine, and one glutamine, the latter replacing the methionine typically, found in mononuclear blue copper proteins. The Cu-Gln bond is one of the, shortest axial ligand bond distances observed to date in structurally, characterized type I copper proteins. The characteristic spectroscopic, properties and electron transfer reactivity of stellacyanin, which differ, significantly from those of other well-characterized cupredoxins, can be, explained by its more exposed copper site, its distinctive amino acid, ligand composition, and its nearly tetrahedral ligand geometry. Surface, features on the cucumber stellacyanin molecule that could be involved in, interactions with putative redox partners are discussed.
About this StructureAbout this Structure
1JER is a Single protein structure of sequence from Cucumis sativus with CU as ligand. Structure known Active Site: CU. Full crystallographic information is available from OCA.
ReferenceReference
A missing link in cupredoxins: crystal structure of cucumber stellacyanin at 1.6 A resolution., Hart PJ, Nersissian AM, Herrmann RG, Nalbandyan RM, Valentine JS, Eisenberg D, Protein Sci. 1996 Nov;5(11):2175-83. PMID:8931136
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