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Effects of Surface Charge on Denaturation of Bovine Carbonic Anhydrase
Author(s) -
Gitlin Irina,
Gudiksen Katherine L.,
Whitesides George M.
Publication year - 2006
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.200600191
Subject(s) - chemistry , denaturation (fissile materials) , carbonic anhydrase , guanidinium chloride , urea , carbonic anhydrase ii , guanidine , ionic strength , sodium dodecyl sulfate , thermal stability , chromatography , inorganic chemistry , enzyme , organic chemistry , nuclear chemistry , aqueous solution
This work compares the denaturation of two proteins—bovine carbonic anhydrase II (BCA) and its derivative with all lysine groups acetylated (BCA‐Ac 18 )—by urea, guanidinium chloride (GuHCl), heat, and sodium dodecyl sulfate (SDS). It demonstrates that increasing the net negative charge of the protein by acetylation of lysines reduces its stability to urea, GuHCl, and heat, but increases its kinetic stability (its thermodynamic stability cannot be measured) towards denaturation by SDS. Increasing the ionic strength of the buffer improves the stability of BCA‐Ac 18 to urea and heat, but still leaves it less stable than unacetylated BCA to those denaturants. In urea, the large change in electrostatic interactions not only modifies the free energy of denaturation, but also introduces a stable intermediate into the unfolding pathway. This work shows that modifications of charges on the surfaces of proteins can have a large effect—positive or negative, depending on the denaturant—on the stability of the proteins despite the exposure of these charges to high dielectric solvent and buffer ions.