42 



VIRUSES 



various conditions. A sort of reaction velocity constant can be calculated for 

 the reaction by this means. Such velocity constants were determined in a vari- 

 ety of buffers at different temperatures. In Figure 34 the logarithm of the 

 velocity constant is plotted against the reciprocal of the absolute temperature 

 for several of the buffers . 



FIGURE 34 - LOG SPECIFIC REACTION VELOCITY OV DESTRUCTION OH' 

 HEMAGGLUTININ OF PR 8 INFLUENZA A PLOTTED AS A FUNCTION OF RECIP- 

 ROCAL OF ABSOLUTE TEMPERATURE. O - Phosphate buffer pH 7 •86, - 

 i'hosphate at pH 7.59, - Phosphate at pH 7.1?. - Phosphate at 

 pH 6.47, - Ammonia buffer at pH 9.55; - Phosphate at pH 6.47 

 tdifferent virus preparation;, - Acetate at pH 5«76. (M.A. 

 Lauffer and iil.M. Scott, Arch. Biochem. 9, 75 (1946 J ). 



Prom these plots the reaction velocity constant at a particular temperature can 

 *e read off for each buffer, in Figure 35 the logarithm of the specific react- 

 ion velocity at 5^° C. for the destruction of hemagglutinin is plotted as a 

 function of pH. 



L.Jio K It 55' 



-3 -; -I g 



— I 1 1 r 



-A -3 -2 -I 



-4 



— I- 



FIGURE 35 - LOG SPECIFIC REACTION VELOCITY AT ^5° C. FOR DESTRUCTION 

 OF HEMAGGLUTININ OF PR 8 INFLUENZA A VIRUS PLOTTED AS A FUITCTION OF pH. 

 (M.A. Lauffer and E.M. Scott, Arch. iJiochem. 9, 75 (19^6; ;. 



It can be seen that the reaction has a minimum rate at pH 8.4. This means that 

 the hemagglutinin has a maximum stability at 55° C. at pH 8.4. it is interest- 

 ing to observe that the isoelectric point of influenza virus A is at pH 5«4-. 



