1ucj | pdb_00001ucj

Mutants of RNase Sa

spinqualitylabelsall models 1ucj, resolution 1.81Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1ucj is a 2 chain structure with sequence from Kitasatospora aureofaciens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.81Å Ligands: SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RNSA_KITAU 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 We previously suggested that proteins gain more stability from the burial and hydrogen bonding of polar groups than from the burial of nonpolar groups (Pace, C. N. (2001) Biochemistry 40, 310-313). To study this further, we prepared eight Thr-to-Val mutants of RNase Sa, four in which the Thr side chain is hydrogen-bonded and four in which it is not. We measured the stability of these mutants by analyzing their thermal denaturation curves. The four hydrogen-bonded Thr side chains contribute 1.3 +/- 0.9 kcal/mol to the stability; those that are not still contribute 0.4 +/- 0.9 kcal/mol to the stability. For 40 Thr-to-Val mutants of 11 proteins, the average decrease in stability is 1.0 +/- 1.0 kcal/mol when the Thr side chain is hydrogen-bonded and 0.0 +/- 0.5 kcal/mol when it is not. This is clear evidence that hydrogen bonds contribute favorably to protein stability. In addition, we prepared four Val-to-Thr mutants of RNase Sa, measured their stability, and determined their crystal structures. In all cases, the mutants are less stable than the wild-type protein, with the decreases in stability ranging from 0.5 to 4.4 kcal/mol. For 41 Val-to-Thr mutants of 11 proteins, the average decrease in stability is 1.8 +/- 1.3 kcal/mol and is unfavorable for 40 of 41 mutants. This shows that placing an [bond]OH group at a site designed for a [bond]CH3 group is very unfavorable. So, [bond]OH groups can contribute favorably to protein stability, even if they are not hydrogen-bonded, if the site was selected for an [bond]OH group, but they will make an unfavorable contribution to stability, even if they are hydrogen-bonded, when they are placed at a site selected for a [bond]CH3 group. The contribution that polar groups make to protein stability depends strongly on their environment. The contribution of polar group burial to protein stability is strongly context-dependent.,Takano K, Scholtz JM, Sacchettini JC, Pace CN J Biol Chem. 2003 Aug 22;278(34):31790-5. Epub 2003 Jun 10. PMID:12799387 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease 3D structures

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