Isoelectric points heat effect

Although DEAE-cellulose apparently fractionated BSA with respect to its sulfhydryl content, the separation of mercaptalbumin and nonmer-captalbumin was achieved on the basis of their isoelectric points. The different components were stable and not interconvertible on reversible denaturation with 6 M urea but differed in their thermal and acid dena-turation properties (Spencer and King, 1971). Fractions with higher isoelectric points had higher solubility-pH profiles and were more susceptible to heat denaturation. However, only 1 unit charge difference between the major components was observed, and it is hard to visualize how such a small difference can contribute so perceptibly to the stability of the molecule. Other unknown factors may have been superimposed on the isoelectric point differences and may have led to the observed effects. 

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