 |
PDBsum entry 1qkx
|
|
|
|
|
 |
Contents |
 |
|
|
|
|
|
|
|
|
|
|
* Residue conservation analysis
|
|
|
|
|
References listed in PDB file
|
|
|
Key reference
|
|
|
Title
|
|
Thermodynamic and structural characterization of asn and ala residues in the disallowed ii' Region of the ramachandran plot.
|
|
|
Authors
|
|
M.C.Vega,
J.C.Martínez,
L.Serrano.
|
|
|
Ref.
|
|
Protein Sci, 2000,
9,
2322-2328.
[DOI no: ]
|
|
|
PubMed id
|
|
|
|
|
|
Abstract
|
|
|
Residue Asn47 at position L1 of a type II' beta-turn of the alpha-spectrin SH3
domain is located in a disallowed region of the Ramachandran plot (phi = 56 +/-
12, psi = -118 +/- 17). Therefore, it is expected that replacement of Asn47 by
Gly should result in a considerable stabilization of the protein. Thermodynamic
analysis of the N47G and N47A mutants shows that the change in free energy is
small (approximately 0.7 kcal/mol; approximately 3 kJ/mol) and comparable to
that found when mutating a Gly to Ala in a alpha-helix or beta-sheet. X-ray
structural analysis of these mutants shows that the conformation of the
beta-turn does not change upon mutation and, therefore, that there is no
relaxation of the structure, nor is there any gain or loss of interactions that
could explain the small energy change. Our results indicate that the energetic
definition of II' region of the Ramachandran plot (phi = 60 +/- 30, psi = -115
+/- 15) should be revised for at least Ala and Asn in structure validation and
protein design.
|
|
|
|
|
|
|
