Crawford S W, Mecham R P, Sage H
Biochem J. 1986 Nov 15;240(1):107-14. doi: 10.1042/bj2400107.
The structural relationships and intermolecular organization among the proteins associated with pulmonary surfactant are largely unknown. We studied the pulmonary-surfactant-associated proteins in the bronchoalveolar lavage fluid obtained from a patient with the clinical syndrome of alveolar proteinosis. The major proteins with Mr values of 32,000-36,000 and 62,000 formed thiol-dependent complexes (Mr greater than 400,000) with intermolecular disulphide bonds present in the collgenase-sensitive domains of these proteins. In contrast, other proteins, which were collagenase-insensitive, formed thiol-dependent oligomers that were not covalently linked to the major proteins. The associations of these proteins in the surfactant of a normal individual were similar. By amino acid analysis, two-dimensional peptide mapping and bacterial-collagenase digestion the 32,000-36,000-Mr and 62,000-Mr proteins were nearly identical. Differences in CNBr cleavage products suggested that the larger of the proteins was formed by non-disulphide, covalent, cross-links in the collagenase-sensitive domains of the 32,000-36,000-Mr proteins. Thus the evidence suggested that the lipid-associated proteins of Mr 32,000-36, 000 contained both disulphide and non-disulphide cross-links in the collagen-like N-terminal region of the proteins and form higher-Mr complexes. This organization may support the three-dimensional conformation of surfactant in the alveolar space.
与肺表面活性物质相关的蛋白质之间的结构关系和分子间组织在很大程度上尚不清楚。我们研究了从一名患有肺泡蛋白沉积症临床综合征的患者获取的支气管肺泡灌洗液中的肺表面活性物质相关蛋白。分子量为32,000 - 36,000和62,000的主要蛋白质与这些蛋白质胶原酶敏感结构域中存在的分子间二硫键形成硫醇依赖性复合物（分子量大于400,000）。相比之下，其他对胶原酶不敏感的蛋白质形成硫醇依赖性寡聚物，这些寡聚物与主要蛋白质没有共价连接。正常个体表面活性物质中这些蛋白质的关联情况相似。通过氨基酸分析、二维肽图谱分析和细菌胶原酶消化，分子量为32,000 - 36,000和62,000的蛋白质几乎相同。溴化氰裂解产物的差异表明，较大的蛋白质是由分子量为32,000 - 36,000的蛋白质的胶原酶敏感结构域中的非二硫键共价交联形成的。因此，证据表明分子量为32,000 - 36,000的脂质相关蛋白质在蛋白质的胶原样N端区域同时含有二硫键和非二硫键交联，并形成更高分子量的复合物。这种组织形式可能支持肺泡空间中表面活性物质的三维构象。
