Brain lipids from the porpoise (Delphinus delphis). Phosphoglycerides rich in isovaleric acid and long-chain iso-acids.

The whole brain of a porpoise (Delphinus delphis) comprised 23.1 wt% of phospholipids on a dry weight basis. Ethanolamine phosphoglycerides (36.6 wt%), choline phosphoglycerides (27.3 wt%), and serine phosphoglycerides (16.9 wt%) were the major components of the phospholipids. A unique feature of the data was the occurrence of large amounts of isovaleric acid in choline phosphoglucerides (28.1 mol%) and ethanolamine phosphoglycerides (6.4 mol%), together with 11.6 and 15.2 mol% of long-chain (C11--C16) iso-acids, respectively. Interestingly, serine phosphoglycerides did not contain detectable amounts of isovaleric acid although trace amounts of long-chain iso-acids were present. No previous evidence exists to show that appreciable amounts of a short-chain acid can be accommodated in animal phospholipids. The occurrence of isovaleric acid in the principal phosphoglycerides of the porpoise brain elicits an interest in how such an anomalous structure is accommodated in the lipid bilayers of the neural membranes.