PLANT AGGLUTININS (LECTINS) II 



72> 



and Shapleigh, 1954a; Bird, 1959). Boyd, Shapleigh, and McMaster 

 made a quantitative study of the precipitin reaction of their partially 

 purified lima bean anti-A and purified A antigenic substance from 

 hog stomach. The general course of the precipitin reaction was found 

 to be very similar to that of the precipitation of A substance by hu- 

 man anti-A antibody (Fig. 6-1). 



5 10 15 20 25 30 35 40 45 50 



Micrograms A substance added 

 Fig. 6-1. Protein nitrogen specifically precipitated from anti-A lima bean 

 lectin solution (open circles) by hog A substance, compared with nitrogen 

 precipitated from human anti-A serum (solid circles). 



A characteristic of the lectins, and one that strikingly differentiates 

 them from immune antibodies, is their homogeneity. I do not mean 

 physical homogeneity, for in most cases the lectins have not been 

 purified sufficiently for us to know whether they are electrophoretically 

 and ultracentrifugally homogeneous.* I mean they are homogeneous 

 in their affinity for red cell antigens. 



* By eluting proteins of different mobilities from paper electrophoresis paper, 

 Ensgraber, Kriipe and Ensgraber-Hattingen (1960) obtained evidence sug- 

 gesting that the agglutinins of twelve species studied by them were not 

 homogeneous electrophoretically. In two cases they were able to obtain fractions 

 of the total agglutinin present that did seem to be electrophoretically (and 

 ultracentrifugally) homogeneous. 



