PDBsum entry 1fev

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Hydrolase PDB id
Protein chains
15 a.a.
101 a.a. *
Waters ×42
* Residue conservation analysis
PDB id:
Name: Hydrolase
Title: Crystal structure of the ala4aib mutation in rnase s
Structure: S peptide. Chain: a. Engineered: yes. S protein. Chain: b. Synonym: rnase s. Ec:
Source: Synthetic: yes. Other_details: s peptide is a 16 residue synthetic peptide with ala4aib replacement. Bos taurus. Cattle. Organism_taxid: 9913. Tissue: pancreas
Biol. unit: Dimer (from PQS)
2.25Å     R-factor:   0.191     R-free:   0.229
Authors: G.S.Ratnaparkhi,R.Varadarajan
Key ref: G.S.Ratnaparkhi et al. (2000). Structural and thermodynamic consequences of introducing alpha-aminoisobutyric acid in the S peptide of ribonuclease S. Protein Eng, 13, 697-702. PubMed id: 11112508
23-Jul-00     Release date:   09-Aug-00    
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Protein chain
Pfam   ArchSchema ?
P61823  (RNAS1_BOVIN) -  Ribonuclease pancreatic
150 a.a.
15 a.a.*
Protein chain
Pfam   ArchSchema ?
P61823  (RNAS1_BOVIN) -  Ribonuclease pancreatic
150 a.a.
101 a.a.
Key:    PfamA domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Enzyme reactions 
   Enzyme class: Chains A, B: E.C.  - Pancreatic ribonuclease.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Endonucleolytic cleavage to nucleoside 3'-phosphates and 3'-phosphooligonucleotides ending in C-P or U-P with 2',3'-cyclic phosphate intermediates.
 Gene Ontology (GO) functional annotation 
  GO annot!
  Biochemical function     nucleic acid binding     2 terms  


Protein Eng 13:697-702 (2000)
PubMed id: 11112508  
Structural and thermodynamic consequences of introducing alpha-aminoisobutyric acid in the S peptide of ribonuclease S.
G.S.Ratnaparkhi, S.K.Awasthi, P.Rani, P.Balaram, R.Varadarajan.
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.

Literature references that cite this PDB file's key reference

  PubMed id Reference
17868092 G.R.Marshall, J.A.Feng, and D.J.Kuster (2008).
Back to the future: ribonuclease A.
  Biopolymers, 90, 259-277.  
12465037 R.Banerjee, and G.Basu (2002).
A short Aib/Ala-based peptide helix is as stable as an Ala-based peptide helix double its length.
  Chembiochem, 3, 1263-1266.  
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