Mycoplasma fermentans possesses unique α-glycolipid antigens (GGPL-I and GGPL-III) at the cytoplasm membrane, which carry a phosphocholine group at the sugar primary (6-OH) position. This paper describes a practical synthetic pathway to a GGPL-I homologue (C16:0) and its diastereomer, in which our one-pot α-glycosylation method was effectively applied. The synthetic GGPL-I isomers were characterized with 1H NMR spectroscopy to determine the equilibrium among the three conformers (gg, gt, tg) at the acyclic glycerol moiety. The natural GGPL-I isomer was found to prefer gt (54%) and gg (39%) conformers around the lipid tail, while adopting all of the three conformers with equal probability around the sugar position. This property was very close to what we have observed with respect to the conformation of phosphatidylcholine (DPPC), suggesting that the Mycoplasma glycolipids GGPLs may constitute the cytoplasm fluid membrane together with ubiquitous phospholipids, without inducing stereochemical stress.
Mycoplasma fermentans在细胞膜上具有独特的α-
糖脂抗原(GGPL-I和GGPL-III),其中在
糖原位(6-OH)位置携带
磷胆碱基团。本文描述了一种实用的合成路径,用于合成GGPL-I同分异构体(C
16:0)及其对映异构体,其中我们有效地应用了一锅法α-糖基化方法。合成的GGPL-I同分异构体通过
1H NMR光谱表征,以确定在无环
甘油部分的三种构象(
gg、
gt、
tg)之间的平衡。发现天然的GGPL-I同分异构体在脂肪尾部周围更倾向于
gt(54%)和
gg(39%)构象,而在糖位周围则以相等的概率采用所有三种构象。这种特性与我们观察到的
磷脂酰
胆碱(
DPPC)构象非常接近,表明
Mycoplasma的
糖脂GGPLs可能与普遍存在的
磷脂一起构成细胞质膜,而不会引起立体
化学应力。