H-2 ANTIGENS OF THE MOUSE 



55 



cent sialic acid, but no uronic acid, although the material is 

 markedly acidic. The products from successive batches of mice 

 vary considerably in their proportions of lipid and protein and, 

 taking the nitrogen content of the "lipid-free" residue as 14-5 

 per cent, the proportions of lipid and protein can be found from 

 the percentage of nitrogen in the TM2 fraction. The nitrogen 



1000- 



Time (min.) 



Fig. I . The effect of ultrasonic vibration on the haemagglu- 

 tination inhibiting activity of H-2 antigen. 



content of the products of different batches has varied from 1 1 • o 

 to 8- 5 per cent, with lipid from 30 to 50 per cent. The nitrogen 

 content of the TMi fractions is slightly lower than that of the 

 TM2. 



The lipid and protein components can be largely separated by 

 solvent extraction. Removal of hpid with ether at —15°, using 

 poorly active freeze-dried material, resulted in little loss of 



