| Popis: |
The use of thermally forme pH gradients permits macromolecular separations in open-channel isoelectric focusing (IEF), simplifying product recovery, shortening run times and eliminating costly carrier ampholytes. Because of these unique advantages and other limitations this IEF method may effect purifications on a preparative scale more effectively than on an analytical scale where other IEF methods may cover a larger pH range. Heat exchangers at both ends of a 3.18 mm × 5.0 mm × 28.0 mm channel generated the temperature gradient (4°C cm −1 ). Owing to the large temperature dependence of the pH (dpH/d T = −0.028 K −1 ), the Tris—HCl buffer formed the pH gradient in the free solution. In a 25 V cm −1 electric field, a dilute mixture of hemoglobin variants A and S ( ca. 0.8 mg mg −1 , isoelectric points 6.98 and 7.2, respectively) were separated and concentrated by a factor of 20. |
