Electrophoresis, analytical disc

Figure 3. Analytical disc gel electrophoresis of purified cellobiase in high and low pH gel systems. A total of 35 pgrams of purified cellobiase was used as the enzyme sample in each gel. The gels were stained for protein with Coomassie blue. The right-hand gel was obtained at a running pH of 4.5 toward the cathode and the left-hand gel at a running pH of 9.5 toward the anode (49).

Analytical disc gel electrophoresis showed that fraction III contained a mixture of proteins whereas fraction II contained one highly purified protein. We therefore decided to use preparative disc gel electrophoresis... 

Figure 4, Analytical disc gel electrophoresis of the hydrocellulases A, B, and C. Hydrocellulases A, B, and C were run in gels A, B, and C respectively. A total of 30 fjigrams of protein was used as the enzyme sample in each gel. Gel D is the pattern obtained when 100 ixgrams of water fraction protein was used as the sample. Gels were stained with Amido-Schwarz (53).

Analytical Disc Electrophoresis. The FSH preparation subjected to polyacrylamide gel electrophoresis according to the method of Davies (1964) and Ornstein (1964) at pH 9.1 and l C showed two bands, as illustrated in Fig. 4. 

The Laemmli SDS-PAGE protocol is one of the most important analytical techniques in analytical protein separation. It is a system with discontinuous pH gradient (disc electrophoresis) and consists of a stacking and a separation gel different in acrylamide concentration and pH. The separation gel may be formed with homogenous acrylamide concentration or with an increasing gradient. 

Purified preparations of alkaline phosphatase from E. coli, judged homogeneous when examined in the analytical ultracentrifuge, contain several isozymes, because several bands which contain enzymic activity are obtained in starch-gel and disc-gel electrophoresis. Although most workers find three bands (38, 39, 41, 43, 69), four (44) and five (70) equally spaced bands have been found. 

Capillary electrophoretic methods including open-column zone electrophoresis, disc electrophoresis in gels, isotachophoresis and isoelectric focusing have received considerable attention from the analytical community over the last three or four years (80, 81, 82). In capillary zone electrophoresis (CZE), nanogram quantities of sample are placed in a silica capillary, 50 to 300 miaons in diameter and 50 to 100 cm long. Since the small dimensions of the capillary allow for efficient removal of Joule heat, electrical fields up to 350 V/cm can be applied. Under the influence of the field, sample components separate by zone electrophoresis while they are carried downstream by electro-osmosis. 

During the first decade of the insulin era, only an acid solution of an impure form of the hormone was available for therapy. When it became possible to crystallize insulin, the purity, and hence the biological potency, of the hormone improved substantially (Table I). These improvements were mainly achieved by introduction of Ztf+-crystallization (Scott, 1934) and recrystallization methods, the latter based on the observation that insulin recrystallized several times was better tolerated by patients suffering from allergic reactions (Jorpes, 1949). Until the late 1960s, recrystallized insulin was considered to be an essentially pure substance, but the introduction of new analytical methods made it possible to detect the presence of significant amounts of protein impurities by disc electrophoresis (Mirsky and... 

On an analytical scale, one can separate the L and H chains, after cleavage of interchain disulfide bonds, by zone electrophoresis in the presence of a dissociating agent, e.g., concentrated urea or detergent (2,8). (For example, in urea-starch gel at low pH, L chains move more rapidly than H chains toward the cathode.) Conventional or disc electrophoresis in polyacrylamide gel has also been used frequently for analytical purposes (9,10). 

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