Fourier transform infrared and differential scanning calorimetric studies of a surface-active material from rabbit lung.
Fourier transform infrared and differential scanning calorimetric studies of a surface-active material from rabbit lung.
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兔肺表面活性材料的傅里叶变换红外和差示扫描量热研究。
DOI：
10.1016/0005-2736(87)90349-x
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Mendelsohn,R
中科院分区：
文献类型：
--
作者：
Mautone,AJ;Reilly,KE;Mendelsohn,R
从兔肺灌洗液中分离出一种表面活性材料，其化学成分与肺表面活性剂一致，并且能够将 Wilhelmy 天平上的表面张力降低至约 6 mN/m。利用傅里叶变换红外光谱（FT-IR）和差示扫描量热法（DSC）技术表征了热致性能。 FT-IR 熔解曲线是根据 2850 cm−1 附近脂质 CH2 对称伸缩振动频率的温度依赖性构建的。观察到起始温度为约 22°C、完成温度为约 38°C 的宽范围凝胶-液晶相变，样品与样品之间的温度存在轻微变化。在 DSC 吸热曲线中注意到类似的完成温度。 Ca2+(5–10 mM) 增加了脂质熔化事件的起始温度，并在所有研究温度下诱导表面活性剂及其脂质提取物的排序。对脂质的影响表明由离子与磷脂酰甘油和其他酸性成分结合引起的 Ca2+ 诱导的相分离。 Ca2+ 和磷酸基团之间直接相互作用的证据是通过 Ca2+ 诱导的 1090 cm−1 对称 PO2 拉伸频率的小变化得出的。从 10:1（脂质/蛋白质，w/w）样品中去除大部分蛋白质成分会导致所得脂质组分的排序。相比之下，从 20:1 样品中去除大部分蛋白质成分不会导致脂质顺序或热致行为发生变化。这些观察结果是根据 Ca2+ 和蛋白质在表面活性剂扩散中所起的作用进行讨论的。 FT-IR 从复杂的生物组织中获取有用的结构信息的能力得到了证明。
A surface-active material with a chemical composition consistent with lung surfactant and with the ability to lower surface tension on a Wilhelmy balance to about 6 mN/m, has been isolated from rabbit pulmonary lavage. The thermotropic properties have been characterized with the techniques of Fourier transform infrared spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). FT-IR melting curves were constructed from the temperature-dependence of the lipid CH2symmetric stretching vibrational frequencies near 2850 cm−1. A broad gel-liquid crystal phase transition with an onset temperature of about 22°C, and a completion temperature of about 38°C was observed, with slight sample-to-sample variations in temperatures. A similar completion temperature was noted in DSC endotherms. Ca2+(5–10 mM) increased the onset temperature of the lipid-melting event, and induced an ordering of surfactant and of its lipid extract at all temperatures studied. The effect on the lipids was suggestive of a Ca2+-induced phase separation caused by ion binding to phosphatidylglycerol and other acidic components. Evidence for a direct interaction between Ca2+and the phosphate groups was suggested through small Ca2+-induced shifts in the 1090 cm−1symmetric PO2stretching frequency. Removal of most of the protein component from a 10:1 (lipid/protein, w/w) sample caused an ordering of the resultant lipid fractions. In contrast, removal of most of the protein component from a 20:1 sample resulted in no change in lipid order or thermotropic behavior. These observations are discussed in light of the roles played both by Ca2+and protein in the spreading of surfactant. The power of FT-IR to acquire useful structural information from complex biological tissues is demonstrated.