Identification of Hemagglutinin of Jack Bean with Concanavalin A

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Abstract
The hemagglutinin of the jack bean is identical with Concanavalin A since the crystallin protein is readily digested by pepsin with a simultaneous loss in hemagglutinating activity. A method is given whereby 2.5% of recrystallized Concanavalin A may be obtained from the jack bean. The protein is inactivated by dilute acid and alkali but the inactivation by acid is reversible. The theory that agglutination is due to neutralization of oppositely charged particles can not be true since the isoelectric point of Concanavalin A is at pH 5.5 and agglutination takes place readily between pH 5.2 and pH 7.5. The crystallin protein agglutinates the erythrocytes of certain animal species, emulsions of many varieties of fat and suspensions of starch and bacteria. It also precipitates solutions of glycogen and inuco-proteins.-The reaction between glycogen and Concanavalin A, and the mechanism of agglutination, were investigated. A theory is proposed, that a hydrophilic substance is changed to a hydrophobic substance and the electric charge is neutralized by the electrolytes. Conclusive evidence is given that the hemagglutinin reacts with the stroma of the red cell. A distinction is made between binding agglutinin and possessing the ability to become agglutinated. The toxic action of Concanavalin A is probably due to its hemagglutinating action.

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