Hao Q, Ding T, Zhang Y, Liu G, Yan L, Gao G, Yan G, Yao Q, Li Q
Department of Molecular Biology, Jilin University, Changchun, China.
Mol Membr Biol. 1997 Jan-Mar;14(1):19-23. doi: 10.3109/09687689709048165.
Saporin-S6 (SO-6) is a type-1 ribosome-inactivating protein purified from the seeds of Saponaria officinalis. The fluorescence characteristics of SO-6 were studied in the presence and absence of phospholipids. The interaction of SO-6 with DMPG or DMPC vesicles results in a decrease in the fluorescence emission intensity of tryptophan without any shift in the emission maximal wavelength. The results of fluorescence titration indicate that DMPG/SO-6 saturation molar ratio is 100: 1, but the binding of DMPC with SO-6 does not reach a saturating plot. A shielding of the tryptophan fluorescence from quenching by acrylamide on interaction with the phospholipids was observed, and this shielding was more pronounced in the presence of DMPG. The interaction of SO-6 with DMPG vesicles is stronger in the liquid-crystalline phase than in the gel phase. Extrinsic fluorescence studies indicated that the interaction of the protein with DMPG vesicles does not modify the phase transition temperature of the lipid, but decreases the amplitude of the change of fluorescence anisotropy associated with the co-operative melting of 1,6-diphenyl-1,3,5-hexatriene (DPH)-labelled vesicles. These results indicate that both electrostatic and hydrophobic components are involved in the SO-6-lipid vesicle interaction.
皂草素 - S6（SO - 6）是一种从肥皂草种子中纯化得到的1型核糖体失活蛋白。研究了在有和没有磷脂存在的情况下SO - 6的荧光特性。SO - 6与二肉豆蔻酰磷脂酰甘油（DMPG）或二肉豆蔻酰磷脂酰胆碱（DMPC）囊泡的相互作用导致色氨酸的荧光发射强度降低，而发射最大波长没有任何偏移。荧光滴定结果表明，DMPG/SO - 6的饱和摩尔比为100:1，但DMPC与SO - 6的结合未达到饱和曲线。观察到与磷脂相互作用时，丙烯酰胺对色氨酸荧光猝灭的屏蔽作用，并且在DMPG存在下这种屏蔽作用更明显。SO - 6与DMPG囊泡在液晶相中的相互作用比在凝胶相中更强。外在荧光研究表明，该蛋白与DMPG囊泡的相互作用不会改变脂质的相变温度，但会降低与1,6 - 二苯基 - 1,3,5 - 己三烯（DPH）标记囊泡协同熔化相关的荧光各向异性变化的幅度。这些结果表明，静电和疏水成分都参与了SO - 6 - 脂质囊泡的相互作用。
