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Selective and specific ion binding on proteins at physiologically‐relevant concentrations
Author(s) -
Miao Linlin,
Qin Haina,
Koehl Patrice,
Song Jianxing
Publication year - 2011
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/j.febslet.2011.08.048
Subject(s) - chemistry , salt (chemistry) , titration , nuclear magnetic resonance spectroscopy , protein folding , residue (chemistry) , folding (dsp implementation) , heteronuclear single quantum coherence spectroscopy , cytoplasm , biochemistry , solubilization , biophysics , stereochemistry , inorganic chemistry , biology , organic chemistry , electrical engineering , engineering
Insoluble proteins dissolved in unsalted water appear to have no well‐folded tertiary structures. This raises a fundamental question as to whether being unstructured is due to the absence of salt ions. To address this issue, we solubilized the insoluble ephrin‐B2 cytoplasmic domain in unsalted water and first confirmed using NMR spectroscopy that it is only partially folded. Using NMR HSQC titrations with 14 different salts, we further demonstrate that the addition of salt triggers no significant folding of the protein within physiologically relevant ion concentrations. We reveal however that their 8 anions bind to the ephrin‐B2 protein with high affinity and specificity at biologically‐relevant concentrations. Interestingly, the binding is found to be both salt‐ and residue‐specific.