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目的 以单纯胰岛素为对照 ,采用傅立叶红外转换光谱 (FourierTransformInfraredFTIR)研究包裹在脂质体内部胰岛素二级结构的变化。方法 分别对单纯胰岛素、胰岛素与空白脂质体混合物 (样品I)及包裹胰岛素的脂质体 (样品II)样品进行FTIR测定。结果 与单纯胰岛素相比 ,样品Ⅰ和Ⅱ与胰岛素的FTIR谱图形状基本一致 ,仅其中的α -螺旋略有下降 (由36 %分别到 32 %～ 31% ) ,β 折叠略有增加 (由 4 8%分别到 5 3%～ 5 1% )。样品I同样品II相比 ,胰岛素的二级结构无明显差别(α 螺旋分别为 32 %～ 31% ,β 折叠分别为 5 3%～ 5 1% )。说明包裹在脂质体内的胰岛素未与脂质体的膜发生插膜作用 ,所产生与单纯胰岛素二级结构之间微小差别的原因是由于部分胰岛素铺展在脂质体膜表面所致的。结论 FTIR测定被载体包裹的蛋白多肽药物的二级结构 ,具有快速直接和非破坏性的特点。经FTIR测定 ,包裹在脂质体内的胰岛素与单纯胰岛素的二级结构相比无明显的变化 ,仍保持原胰岛素的二级结构
Objective To study the changes of secondary structure of insulin encapsulated in liposomes by Fourier Transform Infrared Fourier Transform Spectroscopy (FTIR). Methods FTIR measurements were performed on samples of simple insulin, insulin and blank liposome mixtures (sample I), and insulin-laden liposomes (sample II), respectively. Results Compared with simple insulin, the FTIR spectra of samples Ⅰ and Ⅱ were almost the same as those of insulin. Only α - helix slightly decreased (from 36% to 32% to 31%, respectively) and β - sheet slightly increased from 48% to 53% ~ 51%, respectively). There was no significant difference in insulin secondary structure between sample I and sample II (α-helix was 32% -31%, β-sheet was 53% -5 51%, respectively). This shows that the insulin encapsulated in the liposome does not intervene with the liposome membrane. The reason for the slight difference between this insulin and the simple insulin secondary structure is that some of the insulin is spread on the surface of the liposome membrane. Conclusion The FTIR method can be used to determine the secondary structure of protein-peptide drugs encapsulated by carrier, which has the characteristics of rapid and direct and non-destructive. Insulin determined by FTIR assay showed that the insulin encapsulated in the liposome had no significant change compared with the secondary structure of insulin alone and still maintained the secondary structure of the original insulin