1n9y

Streptavidin Mutant S27A at 1.5A Resolution

spinqualitylabelsall models 1n9y, resolution 1.53Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1n9y is a 4 chain structure with sequence from Streptomyces avidinii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.53Å Ligands: MPD, MRD Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function SAV_STRAV The biological function of streptavidin is not known. Forms a strong non-covalent specific complex with biotin (one molecule of biotin per subunit of streptavidin). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed An elaborate hydrogen-bonding network contributes to the tight binding of biotin to streptavidin. The specific energetic contributions of hydrogen bonds to the biotin ureido oxygen have previously been investigated by mapping the equilibrium and activation thermodynamic signatures of N23A, N23E, S27A, Y43A and Y43F site-directed mutants [Klumb et al. (1998), Biochemistry, 37, 7657-7663]. The crystal structures of these variants in the unbound and biotin-bound states provide structural insight into the energetic alterations and are described here. High (1.5-2.2 A) to atomic resolution (1.14 A) structures were obtained and structural models were refined to R values ranging from 0.12 to 0.20. The overall folding of streptavidin as described previously has not changed in any of the mutant structures. Major deviations such as side-chain shifts of residues in the binding site are observed only for the N23A and Y43A mutations. In none of the mutants is a systematic shift of biotin observed when one of the hydrogen-bonding partners to the ureido oxygen of biotin is removed. Recent thermodynamic studies report increases of DeltaDeltaG(o) of 5.0-14.6 kJ mol(-1) for these mutants with respect to the wild-type protein. The decreasing stabilities of the complexes of the mutants are discussed in terms of their structures. Structural studies of hydrogen bonds in the high-affinity streptavidin-biotin complex: mutations of amino acids interacting with the ureido oxygen of biotin.,Le Trong I, Freitag S, Klumb LA, Chu V, Stayton PS, Stenkamp RE Acta Crystallogr D Biol Crystallogr. 2003 Sep;59(Pt 9):1567-73. Epub 2003, Aug 19. PMID:12925786 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Avidin 3D structures

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