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Salt‐stabilized globular protein structure in 7 M aqueous urea solution
Author(s) -
Dötsch V.,
Wider G.,
Siegal G.,
Wüthrich K.
Publication year - 1995
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 - 10.1016/0014-5793(95)01004-x
Subject(s) - urea , chemistry , aqueous solution , solvation , globular protein , salt (chemistry) , crystallography , ionic bonding , residue (chemistry) , protein folding , protein structure , inorganic chemistry , ion , organic chemistry , biochemistry
A 7 M aqueous urea solution of the 63‐residue N‐terminal domain of the 434‐repressor at pH 7.5 and 18°C contains a mixture of about 10% native, folded protein and 90% unfolded protein. Interconversion between the two conformations is slow on the NMR chemical shift time scale, so that observation of separate resonances can be used to monitor the equilibrium between folded and unfolded protein when changing the solution conditions. In this paper we describe the influence of various salts or non‐ionic compounds on this conformational equilibrium. Solution conditions are described which contain a homogenous preparation of the folded protein in the presence of 6 to 7 M urea, providing a basis for an NMR structure determination in concentrated urea and for studies of the solvation of the folded protein in mixed water/urea/salt environments.