360 V. BLOOD LIPIDS 



thins to the smallest amount in red cells, in contradistinction to their dis- 

 tribution in plasma. 60 In fact, some investigators question whether or not 

 lecithin is a component of the erythrocytes, since neither Burger and Beu- 

 mer 67 nor Haurowitz and Sladek 68 were able to detect any choline after 

 saponification of the ether-soluble phosphatide fraction from red blood cells. 



a. C. A. Preparation. Macheboeuf 5 - 69-71 was the first to prepare a 

 lipoprotein from horse serum which contained phospholipids and chole- 

 sterol. Although as much as 40% of the lipoprotein consisted of lipids, it 

 was water-soluble in neutral or alkaline media at a pH greater than 6.5. 

 This lipoprotein has been referred to as "C.A.," for cenapses precipitated 

 by acid. 



In a more recent publication, Macheboeuf and Rebeyrotte 72 further 

 characterized C.A. In one preparation made before the war, the composi- 

 tion was as follows: protein, 59.3%; lecithin, 22.7% with no cephalin; 

 and cholesterol esters, 17.9% (no free cholesterol). However, in prepara- 

 tions made since the war, in a period when the conditions in France result- 

 ing from the war damage were such that the horses were undernourished, 

 it was impossible to prepare any new C.A. samples with lipid concentrations 

 as high as 40%. A more recent sample had a composition as follows: 

 protein, 83%; lecithin, 12.5%; and cholesterol, 4.5%. The latter prepa- 

 ration had a molecular weight of approximately 85,000; it is believed that 

 one protein molecule is associated with 13 or 14 lecithin molecules, and with 

 5 or 6 moles of cholesterol esters. 



b. Other Lipoprotein Preparations. Blix et alP reported the presence 

 of phospholipids and cholesterol in all of a series of blood proteins separated 

 from each other electrophoretically. The relative percentages of phos- 

 pholipid and cholesterol, respectively, in the several preparations from 

 normal serum were as follows: albumin, 2.25 and 1.07%; a-globulin, 

 7.25 and 4.45%; ,3-globulin, 10.0 and 8.65%; and 7-globulin, 1.0 and 0.41%. 



Adair and Adair 74 prepared a lipoprotein from human serum by precipi- 

 tation at a pH of 7 with 50 to 60% of ammonium sulfate. After purifica- 

 tion by electrophoresis, a homogeneous product was obtained containing 



67 M. Burger and H. Beumer, Biochem. Z., 56, 446-456 (1913). 



68 F. Haurowitz and J. Sladek, Z. physiol. Chem., 173, 268-277 (1928). 



69 M. A. Macheboeuf, Bull. soc. chim. biol., 11, 483-503 (1929). 



70 M. A. Macheboeuf, Rev. gen. colloides, 7, 352-367 (1929). 



71 M. A. Macheboeuf, Rev. gen. colloides, 7, 393-405 (1929). 



72 M. A. Macheboeuf and P. Rebeyrotte, in Lipoproteins, General discussion Faraday 

 Soc, No. 6, 62-74, Aberdeen Univ. Press, Aberdeen, 1949. 



73 G. Blix, A. Tiselius, and H. Svensson, /. Biol. Chem., 137, 484-494 (1941). 



74 G. S. Adair and M. E. Adair, J. Physiol, 102, 17 P (1943). 



