5iix

Crystal structure of Equine Serum Albumin in the presence of 15 mM zinc at pH 6.5

spinqualitylabelsall models 5iix, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5iix is a 1 chain structure with sequence from Equus caballus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.2Å Ligands: SO4, ZN Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function ALBU_HORSE Publication Abstract from PubMed Zinc is an essential nutrient in the body; it is required for the catalytic activity of many hundreds of human enzymes and virtually all biological processes, therefore its homeostasis and trafficking is of crucial interest. Serum albumin is the major carrier of Zn(2+) in the blood and is required for its systemic distribution. Here we present the first crystal structures of human serum albumin (HSA) and equine serum albumin (ESA) in complex with Zn(2+). The structures allow unambiguous identification of the major zinc binding site on these two albumins, as well as several further, weaker zinc binding sites. The major site in both HSA and ESA has tetrahedral geometry and comprises three protein ligands from the sidechains of His67, His247 and Asp249 and a water molecule. Isothermal titration calorimetric studies of a HSA H67A mutant confirm this to be the highest affinity Zn(2+) site. Furthermore, analysis of Zn(2+) binding to HSA and ESA proved the presence of secondary sites with 20-50-fold weaker affinities, which may become of importance under particular physiological conditions. Both calorimetry and crystallography suggest that ESA possesses an additional site compared to HSA, involving Glu153, His157 and His288. The His157 residue is replaced by Phe in HSA, incapable of metal coordination. Collectively, these findings are critical to our understanding of the role serum albumin plays in circulatory Zn(2+) handling and cellular delivery. Circulatory zinc transport is controlled by distinct interdomain sites on mammalian albumins.,Handing KB, Shabalin IG, Kassaar O, Khazaipoul S, Blindauer CA, Stewart AJ, Chruszcz M, Minor W Chem Sci. 2016 Nov 1;7(11):6635-6648. doi: 10.1039/c6sc02267g. Epub 2016 Aug 15. PMID:28567254 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Albumin 3D structures

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