Palestini P, Masserini M, Tettamanti G
Department of Medical Chemistry and Biochemistry, University of Milan, Italy.
FEBS Lett. 1994 Aug 22;350(2-3):219-22. doi: 10.1016/0014-5793(94)00765-9.
The exposure of GM1 molecular species present in the native ganglioside, carrying C18:1 or C20:1 long-chain bases (LCB), to Dactylium dendroides galactose oxidase was studied. When native GM1 (49.3% C18:1 and 50.7% C20:1 LCB, respectively), was inserted in dipalmitoylphosphatidylcholine vesicles and partially oxidized (10%), the proportion of C18:1 and C20:1 species in the oxidized GM1 was 59.6% and 40.4%, respectively, suggesting a preferential action of the enzyme on the shorter species. The Vmax of the enzyme was higher on C18:1 GM1 than on C20:1 GM1. The molecular species were affected without any preference after partial (10%) oxidation of GM1 incorporated in egg phosphatidylcholine vesicles or in micellar form. These data indicate that the exposure of the terminal galactose moiety of GM1 ganglioside to galactose oxidase is affected by the ganglioside ceramide composition as well as the phospholipid environment, that presumably determine the distribution (molecular dispersion, segregation) of the ganglioside within the membrane.
研究了天然神经节苷脂中存在的携带C18:1或C20:1长链碱基（LCB）的GM1分子种类对树状指孢霉半乳糖氧化酶的暴露情况。当天然GM1（分别为49.3% C18:1和50.7% C20:1 LCB）插入二棕榈酰磷脂酰胆碱囊泡并部分氧化（10%）时，氧化型GM1中C18:1和C20:1种类的比例分别为59.6%和40.4%，表明该酶对较短种类具有优先作用。该酶对C18:1 GM1的Vmax高于对C20:1 GM1的Vmax。在掺入卵磷脂酰胆碱囊泡或以胶束形式存在的GM1部分（10%）氧化后，分子种类受到影响，但无任何偏好。这些数据表明，GM1神经节苷脂末端半乳糖部分对半乳糖氧化酶的暴露受神经节苷脂神经酰胺组成以及磷脂环境的影响，这可能决定了神经节苷脂在膜内的分布（分子分散、分离）。
