MITOCHONDRIAL SIRlt I TKK AND Fl'NCTION 93 



TaBLK 2. Mnoi IIONUKIAL Lll'lUS 



^/. Fhi)s|)hati(lyl fthanolaniim- and serine 



Inositol phosphatides 



Lecithin, cephalin 



Sphin.uolipiils 

 B. L\ sopiiosphatides 



PIasmaK)gens 



Lipid cytochrome c 



C. Neutral fats 

 ('holesterol 

 Waxes 

 a-tocopherol 

 Fatty acids 

 Coenzyme Q 

 Carotene 451 111,^ 

 Carotene 447 m^a 

 Carotene 441 m/x 



metals which occur in definite proportions in the electron transfer chain. Iron, in 

 a form other than that of heme iron, is found to be present in all components of 

 the chain, and there are some hints that iron is concerned in the links which bind 

 the different components together in the particle. Copper is also present in the 

 particle, but it is associated exclusively with cytochrome a. Other metals such 

 as Mg^* are always present, but there is as yet no evidence that the bound Mg"'"' is 

 not adventitious metal. 



The electron transport particle contains a bewildering variety of lipids, a partial 

 list of which is given in table 2. The bulk, if not all, the lipid is part of lipoprotein 

 lipid, though some lipids may be associated directly with the flavoprotein or hemo- 

 protein components. 



The succinic and DPNH flavoproteins have both been isolated from the elec- 

 tron transport particle or derivative particles and brought to a state of ultracentri- 

 fugal and electrophoretic homogeneity (31, 4, 26, 13). Cytochromes c and Ci have 

 been isolated as pure components, but b and a have yet to be brought to heel. 

 The work on lipoproteins is in its infancy and the study of the lipid components 

 of the lipoprotein is far from complete. Thus our knowledge of the components 

 of the electron transfer chain is still fragmentary to a degree. 



The electron transfer particle contains the complete respiratory chain for the 

 oxidation of succinate and DPNH by molecular oxygen. Succinate is oxidized to 

 fumarate and DPNH to DPN'. The composition of the electron transport particle 

 from beef heart mitochondria is shown in table 3. For each mole of flavin there 

 are approximately 3 moles of heme, 30 atoms of non-heme iron, and 4 atoms of 



Table 3. Composition of etp 



