A high-pressure sample cell for circular dichroism studies.

The construction and operation of a preparative polyacrylamide-gel electrophoresis system is described. Emerging protein bands are collected by an intermittent pumping system which is based on the design of Brownstone ((1969) Anal. Biochem.27, 25–46). The original pressure-sensitive operation was, however, simplified to time-volume operation. Cooling of the gel by a central cooling finger, essentially according to Jovin et al. ((1964) Anal. Biochem.9, 351–369), has also been added. To accomodate the polyethylene tubing needed for intermittent collection of protein and also the central cooling finger, it is necessary to polymerize the gel in a mold before it is installed in the gel housing compartment of the electrophoresis cell. Gel concentrations of 5% and higher can be used in this system. Dilution of emerging protein samples by the intermittent collection system is kept to a minimum. This fact, together with simplicity of design makes it suitable for general preparative work with polyacrylamide-gel electrophoresis. Operation of the apparatus and resolution of protein bands are demonstrated by separation of bovine serum albumin polymers and thyroxine-binding proteins in human serum.