Distribution of fatty acids in lipids of rat brain, brain mitochondria and microsomes.

The importance of lipids as structural elements of particulate enzyme systems is being increasingly realized (e.g. Green, 1959; Hokin & Hokin, 1959). The extent to which the lipids themselves participate in the metabolic function of the structures in which they are found and the specificity of the lipids for particular structures and functions are uncertain. The present study represents part of a search for lipids of specific structure in subcellular fractions of different organs. The underlying assumption is that the occurrence of a lipid with a particular structure in the corresponding cell organelle (or fraction thereof) of organs with different total lipid composition may give an indication of the metabolic function of the lipid. Experimental data on the detailed composition of lipids in different tissues are scarce, and on the fatty acid distribution within lipids almost nonexistent. In view of the variety of tissues used for research on subcellular organelles, and of the probable metabolic importance of lipids, a more detailed knowledge of tissue lipids is desirable. The present study provides some new data for rat brain, brain mitochondria and microsomes. The study is based on partition of total lipid extracts by silicic acid chromatography and gas-liquidchromatographic analysis of the fatty acid content of separated phospholipids.