[Method of extracting brain proteolipids]

From the whole brain of animals representing 5 classes of vertebrates--mammals (Macaca rhesus and albino rat), birds (the pigeon Columba livia), reptiles (the tortoise Testudo horsfieldi), amphibians (the frog Rana temporaria) and fishes (the trout Salmo irideus), as well as from myelin preparations of mammals (dog, rabbit and rat) proteolipids have been isolated by emulsion--centrifugation method. It was shown that extraction procedure results in the loss and destruction of several proteolipid complexes. In all the animals investigated, the main loss (from 25 to 75% of all complexes) was observed during emulsion--centrifugation stage, especially during 10-min centrifugation at 200 g. During extraction of proteolipids from the whole brain, under the conditions employed, the lost proteolipids are presumably those which belong to the myelin fraction. To prevent excessive proteolipid loss, the final low speed centrifugation step should be avoided. It was shown that in order to obtain proteolipids in a soluble form in a mixture of chloroform and methanol, total proteolipids from the brain of mammals should contain not less than 27% of phospholipids. Studies were also made on the composition and relative content of phospholipids in proteolipids extracted from the whole mammalian brain and myelin preparations. With respect to phospholipid composition, proteolipids from the whole brain significantly differ from those obtained from myelin fraction. Myelin fraction, being itself rich in proteolipids, contain large amounts of phosphatidyl serine (up to 69); however, proteolipids of this fraction contain lower amounts (4%) of diphosphatidyl glycerol as compared to proteolipids from the whole brain (22%).(ABSTRACT TRUNCATED AT 250 WORDS)