Información detallada - 1C54
Ribonucleasa Sa microbiana
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Descripción de la estructura


1C54

Grupo de Compuestos: Ribonucleasas

Descripción : Ribonucleasa Sa microbiana

Referencia PDB : 1C54

Swissprot :

Medline :

Pubmed : 11455593

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Publicación en la que está descrita:






Solution structure and dynamics of Ribonuclease Sa.


D.V. Laurents, J.M. Pérez-Cañadillas, J. Santoro, M. Rico, D. Schell, C.N. Pace and M. Bruix.


Proteins 2001 Vol.44, pp.200-211


DOI: 10.1002/prot.1085







Abstract :







We have used NMR methods to characterize the structure and dynamics of ribonuclease Sa in solution. The solution structure of RNase Sa was obtained using the distance constraints provided by 2,276 NOEs and the C6-C96 disulfide bond. The 40 resulting structures are well determined; their mean pairwise RMSD is 0.76 A (backbone) and 1.26 A (heavy atoms). The solution structures are similar to previously determined crystal structures, especially in the secondary structure, but exhibit new features: the loop composed of Pro 45 to Ser 48 adopts distinct conformations and the rings of tyrosines 51, 52, and 55 have reduced flipping rates. Amide protons with greatly reduced exchange rates are found predominantly in interior beta-strands and the alpha-helix, but also in the external 3/10 helix and edge beta-strand linked by the disulfide bond. Analysis of (15)N relaxation experiments (R1, R2, and NOE) at 600 MHz revealed five segments, consisting of residues 1-5, 28-31, 46-50, 60-65, 74-77, retaining flexibility in solution. The change in conformation entropy for RNase SA folding is smaller than previously believed, since the native protein is more flexible in solution than in a crystal.