Pressure Stability of Proteins at their Isoelectric Points

Gene      Kidman; Hyun      Park; Dexter   B.   Northrop

Abstract

Yeast alcohol dehydrogenase is slowly denatured at moderate hydrostatic pressure (t1 / 2 ? 30 min at 2 kbar and pH 7). The extent of denaturation is pH dependent with maximal stability near the isoelectric point of the protein, pH = 5.4. While not a surprising finding, it appears that this phenomenon has not been documented before (or at least not identified) despite many investigations into the pressure stability of proteins. Consideration of changes in the net charge of proteins far from their isoelectric points may explain other pressure effects as well.

Keywords: Isoelectric point, hydrostatic pressure, yeast alcohol dehydrogenase, myoglobin, volume of ionization, cytochrome c, protein folding, protein denaturation, barostability, thermostability