148 INTRODUCTION TO IMMUNOCHEMICAL SPECIFICITY 



By estimating the molecular weights of the isoagglntinins and by 

 estimating m by determining the amount of protein nitrogen taken 

 up by erythrocytes from agglutinating sera, Wurmser and Filitti- 

 Wurmser were able also to obtain approximate values for the free 

 energy and entropy changes for these anti-B-B reactions. The ap- 

 proximate molecular weights obtained are shown in Table 10-3. 



TABLE 10-3 

 Approximate Molecular Weights of Human Anti-B Isoagglutinins* 



It will be seen that the different kinds of anti-B, according to 

 Wurmser, also differ in molecular weight. 



The calculated free energy and entropy changes are shown in 

 Table 10-4. It will be seen that these results suggest that the binding 

 energies AF° are not very different for the three kinds of anti-B, but 

 that the differences in AH° correspond to significant differences in 

 A^'". Wurmser and Filitti- Wurmser concluded that the specific com- 

 bining groups of the three different kinds of anti-B are not very 

 different and suggested that the increase in entropy which results 

 when the anti-B of group O serum combines with B erythrocytes may 

 be connected with a perturbation of the entire protein molecule, pos- 



TABLE 10-4 



Free Energy and Entropy Changes for Binding of Anti-B Isoagglntinins 

 by B Erythrocytes'' 



Genotype of donor AF°,kcal./mole A5°,e.u. 



GO -9.2 -1-24 



AiAi -9.5 +9.7 



A,0 -9.8 -20 



» Wurmser and Filitti-Wurmser, 1957. 



