Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8291983 | Archives of Biochemistry and Biophysics | 2008 | 8 Pages |
Abstract
Apoflavodoxin from the sulfate reducing bacteria Desulfovibrio desulfuricans is a small, acidic protein with a net charge of â19 at neutral pH. Here, we show that monovalent cations in biologically relevant amounts have dramatic effects on apoflavodoxin stability. The effect is largest for Gdm+ and decreases as a function of increased cation charge density (Gdm+ > NH4+ ⩾ K+ â¼Â Cs+ â¼Â Na+ > Li+). A linear correlation of stabilizing effects with cation hydration properties suggests an important role of dehydration in efficient cation interaction with the protein. The effects on stability are due to preferential binding of one cation to native apoflavodoxin and results in an increase in thermal midpoint of 20 °C and the free energy of unfolding (at 20 °C) increases fivefold. Tuning of biophysical properties (such as folding and ligand/cofactor binding) of acidic proteins by cation binding may be important in vivo.
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Authors
Erik Sedlák, Loren Stagg, Pernilla Wittung-Stafshede,