1fev

CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S

spinqualitylabelsall models 1fev, resolution 2.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1fev is a 2 chain structure with sequence from Bos taurus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: SO4 NonStd Res: AIB Related: 1d5d, 1d5e, 1d5h, 1rnv, 1rbh Activity: Pancreatic ribonuclease, with EC number 3.1.27.5 Resources: FirstGlance, OCA, RCSB, PDBsum Function [RNAS1_BOVIN] Endonuclease that catalyzes the cleavage of RNA on the 3' side of pyrimidine nucleotides. Acts on single stranded and double stranded RNA. 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 The S protein-S peptide interaction is a model system to study binding thermodynamics in proteins. We substituted alanine at position 4 in S peptide by alpha-aminoisobutyric acid (Aib) to investigate the effect of this substitution on the conformation of free S peptide and on its binding to S protein. The thermodynamic consequences of this replacement were studied using isothermal titration calorimetry. The structures of the free and complexed peptides were studied using circular dichroic spectroscopy and X-ray crystallography, respectively. The alanine4Aib replacement stabilizes the free S peptide helix and does not perturb the tertiary structure of RNase S. Surprisingly, and in contrast to the wild-type S peptide, the DeltaG degrees of binding of peptide to S pro, over the temperature range 5-30 degrees C, is virtually independent of temperature. At 25 degrees C, the DeltaDeltaG degrees, DeltaDeltaH degrees, DeltaDeltaS and DeltaDeltaCp of binding are 0.7 kcal/mol, 2.8 kcal/mol, 6 kcal/mol x K and -60 kcal/mol x K, respectively. The positive value of DeltaDeltaS is probably due to a decrease in the entropy of uncomplexed alanine4Aib relative to the wild-type peptide. The positive value of DeltaDeltaH: degrees is unexpected and is probably due to favorable interactions formed in uncomplexed alanine4Aib. This study addresses the thermodynamic and structural consequences of a replacement of alanine by Aib both in the unfolded and complexed states in proteins. Structural and thermodynamic consequences of introducing alpha-aminoisobutyric acid in the S peptide of ribonuclease S.,Ratnaparkhi GS, Awasthi SK, Rani P, Balaram P, Varadarajan R Protein Eng. 2000 Oct;13(10):697-702. PMID:11112508 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ribonuclease Temp

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