An efficient solubilization buffer for plant proteins focused in immobilized pH gradients.

The solubilization of a large array of proteins before electrophoresis itself is a very critical point for proteomic analyses. We compared the efficiency of several different solubilization buffers. From this work, we defined a very efficient solubilization buffer, including two chaotropes, two reducing agents (R2), two detergents (D2), and two kinds of carrier ampholytes in combination. This so-called R2D2 buffer (5 M urea, 2 M thiourea, 2% 3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propane-sulfonate, 2% N-decyl-N,N-dimethyl-3-ammonio-1-propane-sulfonate, 20 mM dithiothreitol, 5 mM Tris(2-carboxyethyl) phosphine, 0.5% carrier ampholytes 4-6.5, 0.25% carrier ampholytes 3-10) proved to be very efficient for a large range of different samples and allowed us to obtain two-dimensional gels of high resolution and quality.