| Popis: |
Myelin consists of compact multilamellae of low density (approx. 1.103). The membrane contains cholesterol, phospholipids, and characteristically cerebroside; only small amounts of ganglioside are found. About 25% of the myelin is protein, mainly proteolipid protein, but a unique basic protein with encephalitogenic properties is also present. The composition of most vertebrate myelin is similar but there are differences in the composition of central and peripheral nerve myelin. Myelin isolated from developing brain has a different composition from that in the adult and it is possible to separate two fractions from “early” myelin (Banik and Davison, 1969; Agrawal et al., 1970). Present methods for the isolation of myelin depend on differential and density gradient centrifugation of nervous tissue homogenates. Several methods are available; choice should be made according to the purpose of the work. Thus the method of Autilio et al. (1964) leads to a highly purified preparation, but myelin and possibly soluble components may be lost during the course of the isolation. The method described here is suitable for isolation of myelin from vertebrate central nervous tissue and leads to myelin fractions which may be further purified by repeated washing if required. |
