Primary structure differences of human surfactant-associated proteins isolated from normal and proteinosis lung

Biochim Biophys Acta. 1992 Apr 14;1138(4):261-7. doi: 10.1016/0925-4439(92)90002-5.


The primary structures of human pulmonary surfactant-associated proteins SP-A, SP-B and SP-C isolated from lung lavage of patients with alveolar proteinosis exhibit significant differences from lung surfactant proteins isolated from lungs of healthy individuals. In contrast to SP-A from normal lungs, proteinosis SP-A was shown by SDS gel electrophoresis to contain large amounts of unreducibly cross-linked beta chains. Specific primary structure modifications of SP-C and SP-B proteins were established by direct molecular weight and structural analysis, using [252Cf]plasma desorption mass spectrometry (PD/MS) as the principal method. In comparison to normal lung surfactant SP-B, proteinosis SP-B showed a significantly increased molecular weight by approx. 500 Da for the unreduced protein dimer. SP-C proteins from normal lungs were identified to possess a bis-cysteinyl-5,6-(thioester)palmitoylated structure, and to contain a frayed N-terminus resulting in two sequences of 34 and 35 amino acid residues. In contrast, SP-C from proteinosis patients was modified by (i) partial or even complete removal of palmitate residues and (ii) additional N-terminal proteolytic degradation. These results indicate the presence of pathophysiological structure modifications, which are likely to occur in the alveolar space, and may lead to a reduced surfactant function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Blotting, Western
  • Chromatography, High Pressure Liquid
  • Glycoproteins / chemistry*
  • Humans
  • Mass Spectrometry
  • Molecular Sequence Data
  • Protein Conformation
  • Proteolipids / chemistry*
  • Pulmonary Alveolar Proteinosis / metabolism*
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants / chemistry*


  • Glycoproteins
  • Proteolipids
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants