AN ISOANTIGENIC LIPOPROTEIN 79 



where destruction of enhancing activity has been shown to occur 

 (Kandutsch and Reinert-Wenck, 1957). Electrophoresis on filter 

 paper or cellulose acetate paper, in a variety of buffers over a pH 

 range from 6-2 to 9, whether Triton was included or omitted 

 from the buffer in the electrode compartments, gave results 

 similar to those obtained with the moving boundary apparatus — 

 only a single component being visible. Attempts at electrophoresis 

 in starch gel met with poor success since the substance trailed 

 from the origin showing a diffuse band. 



Chemical composition: The results of some chemical analyses of 

 TSL are shown in Table II. Since the methods used to determine 



Table II 



Composition of the Triton-soluble lipoprotein 



Percentage of 

 Measurement Method dry weight 



Hexose (Winzler, 1955) 1-8 



Sialic acid (Warren, 1959) 0*13 



Hexosamine (Rosenlund, 1956) 0*6 



Nitrogen Semi-micro-Kjeldahl 14*9 



Phosphorus (King» 1932) i*o 



Lipid Extracted with 2:1 



CHCI3 : methanol 25-8 



hexose, sialic acid and hexosamine are not entirely specific, the 

 values shown for these compounds may be erroneously high. It is 

 clear that carbohydrate constitutes at best only a small portion of 

 the lipoprotein. Lipid extracted with 2 : i CHCI3 : methanol 

 constituted 25-8 per cent of the weight of the TSL and most of 

 the phosphorus present in the TSL was found in the lipid extract. 

 The concentration of phosphorus in the residual protein was only 

 o*i8 per cent as contrasted to i-o per cent in the TSL before 

 extraction. The concentration of nitrogen in the residual protein 

 (14-7 per cent) was similar to that found in the whole lipoprotein. 

 The ultraviolet absorption spectrum of TSL (Fig. 4) shows a peak 

 due to protein in the region of 280 mfx and an additional absorp- 

 tion band in the region 230-260 m(x. The latter band is probably 



