Isoelectric focusing artifacts

Estimates of the isoelectric point of different plasma cholinesterases are shown in Table 10. There is a wide variation within the range pH 3 to 5, which is probably due to artifacts associated with the different methods which were used. Sources of error include evaporation, electroosmosis, and variation in texture of the supporting medium, with consequent variable adsorption of protein. Correction may be made for these factors by the electrophoresis, under identical conditions, of an uncharged reference substance such as dextran (S5, Wl). When subjected to preparative isoelectric focusing, human plasma cholinesterase showed a ma-... 

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