Protein Fractionation and Separation in the Large Tiselius Cell. ∗

Abstract

The Tiselius electrophoresis apparatus introduced to America about 1937 is now commonly found in the leading laboratories throughout the country. The War has focused much effort upon protein solutions, especially serum and plasma, and as a result the Tiselius apparatus found not only immediate but intense application.

In order to separate the fractions obtained by electrophoresis, Tiselius 1 , 2 has used 2 small so-called separation cells. A compensator mechanism made it possible to move mechanically the total protein solution until a desired fraction was concentrated within the upper or lower channel. One or both of the middle sections were slid out of alignment. The supernatant buffer was removed, and finally the fractions in the various compartments were obtained individually by means of an extended steel needle attached to a syringe. Longsworth 3 recently has improved the “convection-proof” pipet technic of Tiselius 4 by lowering a fine glass capillary into the cell and very carefully withdrawing a desired fraction with a fixed syringe-compensator device. The removal of any fraction could be accurately controlled by direct Schlieren observation.

The method of Tiselius is satisfactory but causes undue dilution of the desired component, while the Longsworth technic requires additional apparatus and extreme care, if diffusion is to be avoided.

This note describes a method to separate fractions in the single, large middle section of the Tiselius cell without extra equipment nor danger of diffusion. For example, fresh serum was diluted 1:2.5 with buffer and dialyzed one day in 2 liters of the same buffer. Electrophoresis was carried out in the usual way until the main components were separated almost completely from each other over two-thirds of the length of the channel. The middle section was moved to one side. The glass plug on the side arm of the “open” electrode vessel was removed, and all the buffer above the cell and from part of the main vessel was siphoned off. The middle section was slid back in place again; no movement of solution occurred because of the “closed” electrode vessel. The 3-way stopcock on the side arm of the “closed” electrode vessel was turned to permit continuity between the vessel and compensator syringe.