Fractionation of spectrin by differential precipitation with calcium

The calcium-stimulated ATPase activity of spectrin can be substantially separated from the magnesium-stimulated activity by partial precipitation of spectrin with calcium. The precipitated Ca-ATPase fraction can be dissolved by dialysis against EDTA, and the resulting solution can be polymerized into characteristic spectrin fibrils. The supernatant contains Mg-ATPase and, either before or after dialysis, contains predominantly “torus” forms. The two fractions are essentially identical on gel electrophoresis, being composed primarily of the high molecular weight peptides with a constant level of minor bands. These results imply that the Ca-ATPase is associated firmly with the high molecular weight peptides.     

DIFFICULTIES AND A WAY OUT: A BAYESIAN APPROACH FOR SENSORY DIFFERENCE AND PREFERENCE TESTS

There are some theoretical difficulties in the philosophy and methodology of sensory difference and preference tests. The difficulties lie in the assumption that the subjects have the same response ability, which is in conflict with psychological ideas about the processes of perception and decision. A Bayesian approach may overcome these difficulties by treating the parameter of proportion as a random variable. This paper presents a Bayesian approach for analysis of data from such sensory tests.