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| - | [[Image:1fev.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1fev| PDB=1fev | SCENE= }} | | {{STRUCTURE_1fev| PDB=1fev | SCENE= }} |
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| - | '''CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S'''
| + | ===CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S=== |
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| - | ==Overview==
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| - | 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.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_11112508}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 11112508 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_11112508}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Aib]] | | [[Category: Aib]] |
| | [[Category: Alpha aminoisobutyric acid]] | | [[Category: Alpha aminoisobutyric acid]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 16:14:34 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 1 03:08:29 2008'' |
Revision as of 00:08, 1 July 2008
Template:STRUCTURE 1fev
CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S
Template:ABSTRACT PUBMED 11112508
About this Structure
1FEV is a Protein complex structure of sequences from Bos taurus. Full crystallographic information is available from OCA.
Reference
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
Page seeded by OCA on Tue Jul 1 03:08:29 2008
