Cruz T F, Moscarello M A
J Neurochem. 1985 May;44(5):1411-8. doi: 10.1111/j.1471-4159.1985.tb08777.x.
Myelin and myelin-containing (P3) fractions were prepared from human white matter by discontinuous sucrose gradient centrifugation. The myelin isolated from each of the fractions of different densities was morphologically and biochemically distinct. Light myelin fractions consisted of compact, multilamellar myelin, whereas the denser fractions consisted predominantly of loose myelin with fewer lamellae. The amounts of both basic protein and lipophilin (proteolipid protein) were reduced in the denser fractions. In contrast, the high-molecular-weight components were elevated in the dense fractions. The lipid composition was similar in all the fractions studied. Analysis of basic protein by gel electrophoresis at pH 10.6 revealed differences in basic protein microheterogeneity among the fractions. The light myelin fraction was enriched in the more positively charged basic protein components (components 1, 2, and 3), whereas these components were reduced in the denser fractions. Myelin in the dense fractions was enriched in the more modified forms of basic protein (components 6, 7, and 8). The pattern of microheterogeneity was different for basic protein isolated from myelins of a 2-year-old and an adult brain; the former showed fewer components and mainly the most cationic species. On the other hand, the pattern of microheterogeneity of basic protein isolated from the different density gradient fractions was similar for both ages.
通过不连续蔗糖梯度离心法从人白质中制备髓磷脂和含髓磷脂（P3）组分。从不同密度的每个组分中分离出的髓磷脂在形态和生化方面都有所不同。轻髓磷脂组分由紧密的多层髓磷脂组成，而密度较大的组分主要由层数较少的疏松髓磷脂组成。密度较大的组分中碱性蛋白和亲脂蛋白（蛋白脂质蛋白）的含量均降低。相反，高分子量组分在密度较大的组分中升高。在所研究的所有组分中脂质组成相似。在pH 10.6条件下通过凝胶电泳分析碱性蛋白，结果显示各组分之间碱性蛋白微异质性存在差异。轻髓磷脂组分富含带正电荷更多的碱性蛋白组分（组分1、2和3），而这些组分在密度较大的组分中减少。密度较大的组分中的髓磷脂富含碱性蛋白的更多修饰形式（组分6、7和8）。从2岁儿童和成人脑中分离出的髓磷脂碱性蛋白的微异质性模式不同；前者显示的组分较少，主要是阳离子性最强的种类。另一方面，从不同密度梯度组分中分离出的碱性蛋白的微异质性模式在两个年龄段中相似。
