Premium
pH dependence of the hydrogen exchange in the SH3 domain of α‐spectrin
Author(s) -
Sadqi M.,
Casares S.,
López-Mayorga O.,
Martı́nez J.C.,
Conejero-Lara F.
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02385-2
Subject(s) - spectrin , sh3 domain , chemistry , domain (mathematical analysis) , biophysics , biochemistry , biology , mathematics , proto oncogene tyrosine protein kinase src , cytoskeleton , phosphorylation , cell , mathematical analysis
Using nuclear magnetic resonance we have measured the hydrogen exchange (HX) in the Src homology region 3 (SH3) domain of α‐spectrin as a function of pH*. At very acidic pH* values the exchange of most residues appears to occur via global unfolding, although several residues show abnormally large Gibbs energies of exchange, suggesting the presence of some residual structure in the unfolded state. At higher pH* HX occurs mainly via local or partial unfoldings. We have been able to characterize the coupling between the electrostatic interactions in this domain and the conformational fluctuations occurring under native conditions by analyzing the dependence upon pH* of the Gibbs energy of exchange. The SH3 domain seems to be composed of a central core, which requires large structural disruptions to become exposed to the solvent, surrounded by smaller subdomains, which fluctuate independently.