Neyroz P, Franzoni L, Spisni A, Masotti L, Brand L
Istituto di Chimica Biologica, Facoltà di Medicina e Chirurgia, Università degli Studi di Parma, Italy.
Chem Phys Lipids. 1992 May;61(3):255-63. doi: 10.1016/0009-3084(92)90105-x.
A procedure for the preparation of N-[1-(2-naphthol)]-phosphatidylethanolamine (NAPH-PE) has been developed. The synthesis is based on the Schiff base formation between the NH2 of the phospholipid and the aldehyde moiety of 2-hydroxy-1-naphthaldehyde. Then selective reduction of the imine is used to obtain the stable secondary amine, NAPH-PE. Formation of the intermediate Schiff base and the final product is confirmed by 13C- and 1H-NMR. Similar to free 2-naphthol, the excited-state pKa (pKa*) of its phospholipid derivative appears to be significantly lower than the ground-state pKa. At pH 7.4, the excitation spectrum of NAPH-PE shows no deprotonated species in the ground-state, while the emission spectrum presents a significant contribution of this species. Thus the fluorescent phospholipid exhibits the typical behavior of excited-state proton-transfer probes. NAPH-PE is found to incorporate in dimyristoyllecithin (DML) vesicles. The emission spectrum of the probe inserted in the liposomes is affected by acetate used as a proton acceptor. These properties should also be manifest in other lipid bilayers (e.g., plasma membranes of cells) and used for excited-state proton transfer studies.
已开发出一种制备N-[1-(2-萘酚)]-磷脂酰乙醇胺（NAPH-PE）的方法。该合成基于磷脂的NH2与2-羟基-1-萘甲醛的醛基之间形成席夫碱。然后通过对亚胺进行选择性还原以获得稳定的仲胺NAPH-PE。通过13C-和1H-NMR确认了中间体席夫碱和最终产物的形成。与其游离的2-萘酚类似，其磷脂衍生物的激发态pKa（pKa*）似乎明显低于基态pKa。在pH 7.4时，NAPH-PE的激发光谱在基态下未显示去质子化物种，而发射光谱则显示该物种有显著贡献。因此，这种荧光磷脂表现出激发态质子转移探针的典型行为。发现NAPH-PE可掺入二肉豆蔻酰卵磷脂（DML）囊泡中。插入脂质体中的探针的发射光谱受用作质子受体的乙酸盐影响。这些特性在其他脂质双层（如细胞膜）中也应表现出来，并用于激发态质子转移研究。
