PROTEINS AND LIPOIDS IN CHLOROPLASTS 



375 



Table 14.V 

 "Lipoids" in Leaves (after Chibnall) 



" Iodine value 200 1/, luj r ^ i\ 



*■ Iodine value 150.1'-'^"°^'"^ ^ '"^" degree of unsaturation). 



" Phosphatidic acid (Formula 14.1) is the parent substance of lecithin and cephahn (lecithin contains 

 an additional choline group bound to phosphoric acid). 

 '^ Considerable losses suffered in fractionation. 



Channon (1929), and Smith and Chibnall (1932), and summarized by 

 Chibnall (1939) in table 14. V. These data refer to leaves as a whole; but 

 since, according to table 14. Ill, almost all leaf Hpoids are concentrated 

 in the chloroplasts, they should be considered as valid also for the iso- 

 lated chloroplasts. 



Table 14. V shows that a considerable part of the lipoid fraction is 

 fats of a highly unsaturated character; the proportion of phospholipides 

 is considerable in cabbage leaves, but comparatively small in cocksfoot. 

 Menke (1940') and Bot (1942) also found only a small amount of phos- 

 pholipides in the lipoid fraction of leaves (0.5-1.5% of total dry weight 

 of spinach leaves, according to Menke). This shows how arbitrary is the 

 specific picture of the protein-chlorophyll-phospholipide association in 

 the chloroplasts, suggested by Hubert and reproduced in figure 46. 



Prior to any direct analysis, the presence of 

 phospholipitles in chloroplasts was deduced from 

 some quaUtative observations (r/. Frey-Wyssling 

 1937, 1938). In addition to staining with hpophilic 

 dyes ((/. page 361), whicli does not necessarily re- 

 quire the presence of true lipides, Frey-Wy.ssling 

 referred to the formation of so-called myelin fig- 

 ures. Lecithin (and certain other compounds) have 

 the property of swelling in water with the forma- 

 tion of peculiar jirotubeiances called "myelin tubes." 

 Weber (1933) and Menke (1934) observed thatsimilar Fic;. 47. — Myehn tubes growing 

 outgrowths can be produced in cliloroi)lasts {cf. fig. 47) from chhjiojilasts (after Weber). 



