ELECTROKINETIC PHENOMENA I. THE ADSORPTION OF SERLr~ PROTEINS BY QUARTZ AND PARAFFIN OIL

It is extremely common in laboratory practice to bring a glass, quartz, or paraffin surface into contact with alkaline solutions of dilute serum proteins, but there is not much definite information regarding the adsorption of serum albumin and globulin by these surfaces. The cataphoretic mobility of quartz particles and oil droplets in protein sols will be used here to elucidate more fully the mechanism of adsorption of protein at the phase boundaries between quartz and a paraffin oil with electrolytes. Although the method of cataphoresis does not always show minor variations in quantity or quality of material adsorbed, it nevertheless gives an approach to the determination of any important gross selective adsorption. Quartz and oil droplets seem to adsorb gelatin and egg albumin non-specificially, but this is by no means true for all surfaces. Red ceils of different mammals (1), for example, do not change their cataphoretic mobilities in the presence of small amounts of homologous or heterologous serum proteins. The presence of gelatin is equally ineffective. In fact: even in acid solutions of pH 3.6 uninjured red cells still retain their negative charge in the presence of gelatin (unpublished data). This means that the red cell surface is little if at all changed by the presence of relatively great excess of protein molecules. The biological importance of comparing the cataphoretic mobility of quartz and paraffin oil in the presence of serum is best demonstrated by a few examples. The phagocytosis of inert particles like quartz, car169