Infrared spectroscopic investigations of pulmonary surfactant. Surface film transitions at the air-water interface and bulk phase thermotropism.
Infrared spectroscopic investigations of pulmonary surfactant. Surface film transitions at the air-water interface and bulk phase thermotropism.
复制标题
肺表面活性物质的红外光谱研究。
DOI：
10.1016/s0006-3495(89)82764-x
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发表时间：
1989
影响因子：
3.4
通讯作者：
Mendelsohn,R
中科院分区：
文献类型：
--
作者：
Dluhy,RA;Reilly,KE;Hunt,RD;Mitchell,ML;Mautone,AJ;Mendelsohn,R
用傅里叶变换红外光谱法研究了从牛肺灌洗液中分离得到的完整肺表面活性剂的磷脂组分的分子结构。采用不同的红外光谱取样技术，考察了表面活性剂的两种不同物理状态。采用透射红外实验对体相表面活性剂进行了研究。在这些实验中，通过温度诱导磷脂酰基链CH2拉伸频率的变化来监测大块表面活性剂的热致性行为。在开始温度接近15℃，结束温度接近42℃的情况下，发现了广泛的相变（通过差示扫描量热法证实）。除了体透射实验外，外反射红外光谱还用于检查空气-水界面处的表面活性剂薄膜。当表面压力从0 dyn/cm增加到43 dyn/cm时，表面活性剂的CH2拉伸频率逐渐持续降低。因此，在与体内大肺容量相对应的表面压力下，表面活性剂酰基链主要以有序（反式）结构存在。在0 ~ 43 dyn/cm的压力范围内，CH2拉伸模式的频移与酰基链的连续有序相一致，表明在表面膜的烃区发生了弱合作相变。表面活性剂的压力-面积曲线特别注意到表面膜的转变，并在二维上近似于体相表面活性剂的广泛热致相变。（摘要删节250字）
The molecular structure of the phospholipid component of intact pulmonary surfactant isolated from bovine lung lavage has been examined by Fourier transform infrared spectroscopy. Two different physical states of the surfactant were examined by means of different infrared spectroscopic sampling techniques. Transmission infrared experiments were used to study the surfactant in the bulk phase. In these experiments, the thermotropic behavior of the bulk surfactant was monitored by temperature-induced variations in the phospholipid acyl chain CH2 stretching frequencies. A broad phase transition (confirmed by differential scanning calorimetry) was noted with an onset temperature near 15 degrees C and a completion temperature near 42 degrees C. In addition to the bulk transmission experiments, external reflection infrared spectroscopy was used to examine surfactant films in situ at the air-water interface. As surface pressure was increased from 0 to 43 dyn/cm, a gradual and continuous decrease in the CH2 stretching frequency was noted for the surfactant. Thus, under surface pressures which correspond to large lung volumes in vivo, the surfactant acyl chains exist mostly in the ordered (trans) configuration. The frequency shift in the CH2 stretching mode is consistent with a continuous ordering of the acyl chains upon compression over the pressure range 0–43 dyn/cm, and implies that a weakly cooperative phase transition occurs in the hydrocarbon region of the surface film. The surface film transition is especially noted in the pressure-area curve of the surfactant and approximates in two dimensions the broad thermotropic phase transition of the bulk phase surfactant.(ABSTRACT TRUNCATED AT 250 WORDS)