1zw7

Elimination of the C-cap in Ubiquitin Structure, Dynamics and Thermodynamic Consequences

spinqualitylabelsall models 1zw7, 21 NMR models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1zw7 is a 1 chain structure with sequence from Atcc 18824. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: UBI1, RPL40A (ATCC 18824) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 Single amino acid substitutions rarely produce substantial changes in protein structure. Here we show that substitution of the C-cap residue in the alpha-helix of ubiquitin with proline (34P variant) leads to dramatic structural changes. The resulting conformational perturbation extends over the last two turns of the alpha-helix and leads to enhanced flexibility for residues 27-37. Thermodynamic analysis of this ubiquitin variant using differential scanning calorimetry reveals that the thermal unfolding transition remains highly cooperative, exhibiting two-state behavior. Similarities with the wild type in the thermodynamic parameters (heat capacity change upon unfolding and m-value) of unfolding monitored by DSC and chemical denaturation suggests that the 34P variant has comparable buried surface area. The hydrophobic core of 34P variant is not packed as well as that of the wild type protein as manifested by a lower enthalpy of unfolding. The increased mobility of the polypeptide chain of this ubiquitin variant allows the transient opening of the hydrophobic core as evidenced by ANS binding. Taken together, these results suggest exceptional robustness of cooperativity in protein structures. Elimination of the C-cap in ubiquitin - structure, dynamics and thermodynamic consequences.,Ermolenko DN, Dangi B, Gvritishvili A, Gronenborn AM, Makhatadze GI Biophys Chem. 2007 Mar;126(1-3):25-35. Epub 2006 Apr 5. PMID:16713063 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also 3D structures of ubiquitin

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