Structure and functions of a dimeric form of surfactant protein SP-C: a Fourier transform infrared and surfactometry study
Surfactant proteins SP-B ( M r = 8700, reduced) and SP-C ( M r = 3000–6000, major form, non-reduced) interact with surfactant phospholipids to enhance their surface active properties. In the present study, we describe the structural and functional characteristics of a novel dimeric form of bovine SP...
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Published in | Chemistry and physics of lipids Vol. 63; no. 1; pp. 91 - 104 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Shannon
Elsevier Ireland Ltd
01.11.1992
Elsevier Science |
Subjects | |
Online Access | Get full text |
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Summary: | Surfactant proteins SP-B (
M
r = 8700, reduced) and SP-C (
M
r = 3000–6000, major form, non-reduced) interact with surfactant phospholipids to enhance their surface active properties. In the present study, we describe the structural and functional characteristics of a novel dimeric form of bovine SP-C (
M
r = 9000, non-reduced), which is identified as [SP-C]
2. Dimeric SP-C exhibits surface tension-lowering properties differing from those of monomeric SP-C and enhances the surface properties of bovine SP-B/phospholipid mixtures. Chemical analysis indicated that [SP-C]
2 was not acylated at the cysteinyl residues. Fourier transform-infrared spectroscopy (FT-IR) was utilized to determine the secondary structures of [SP-C]
2 in DPPC films. Relative percentages of α-helical, β-sheet, β-turn and random coil structures were calculated by peak fit analysis of the amide I band of the FT-IR spectra indicating that, in contrast to the helical structure of monomeric SP-C, [SP-C]
2 exhibits almost exclusively β-sheet structure. In addition, only 10% of the amide (backbone) hydrogens exchanged with deuterium of D
2O, indicating that the remaining 90% of amide hydrogens were not accessible to D
2O due to strong hydrogen bonding or their location in a hydrophobic environment. Dimerization of SP-C effects a major change in secondary structure, a factor which may play a role in the interaction of SP-C with phospholipids in pulmonary surfactant. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0009-3084 1873-2941 |
DOI: | 10.1016/0009-3084(92)90026-L |