A concentrating two-phase partitioning: its application to isolation of plasma membrane from maize roots

An improved two-phase partitioning technique, widely applicable to the purification of biological materials, is developed. With this technique, the two-phase system is obtained by mixing only two kinds of single-polymer solutions in appropriate proportions. One of the more distinctive features of this improvement is that the volume ratio between the top and the bottom phase can be changed freely without affecting the equilibrium state of the two-phase partition; this allows concurrent concentration of the objective material of purification with its partition. This technique was adapted from the conventional method of purifying maize root plasma membrane vesicles. By comparison, it was found that the improved method was simple to use, was efficient, and consumed less time and polymer material.