Selective loss of myelin proteins during autolysis.

Rat brains allowed to autolyze in situ for 12 h selectively lost myelin proteins. Basic proteins are markedly decreased, but DM-20 (1) and proteolipid proteins also are lost from the myelin of developing and mature rat brain. At room temperature there is a 50% decrease in the concentration of basic protein in myelin isolated from 15-day-old rats. Reducing the ambient temperature to 0°C reduces the loss to 20%. Similar but less marked changes occur in the brains of adult animals. The molar ratios of cholesterol, phospholipids, and glycolipids are unaffected by autolysis, and there is also no change in the specific activity of the myelin marker enzyme 2',3'-cyclic nucleotide-3'-phosphohydrolase (E.C.3.1.4.37). Electron microscopic examination of the isolated myelin demonstrates multilammelar structure with intraperiod lines.