Fourier transform infrared studies of secondary structure and orientation of pulmonary surfactant SP-C and its effect on the dynamic surface properties of phospholipids

Journal Article · Tue Oct 15 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00105a033· OSTI ID:5822705

Pastrana, B; Mendelsohn, R ^[1]; Mautone, A J ^[2]

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1. Rutgers, The State Univ. of New Jersey, Newark (United States)
2. Univ. of Medicine and Dentistry of New Jersey, Newark (United States)

SP-C, a highly hydrophobic, 3.7-kDa protein constituent of lung surfactant, has been isolated from bovine lung lavage, purified, and reconstituted into binary lipid mixtures of 1,2-dipalmitoylphosphatidylcholine (DPPC) and 1,2-dipalmitoylphosphatidylglycerol (DPPC). Fourier transform infrared (FT-IR) spectroscopy has been applied to examine SP-C secondary structure, the average orientation of {alpha}-helical segments relative to the bilayer normal in membrane films, and the effect of protein on the thermotropic properties of the phospholipid acyl chains. The helical segments exhibited an average angle of orientation of about 24{degree} with respect to the bilayer normal, suggesting a trans-bilayer orientation of the peptide. The observation that 70% of the peptide bond hydrogens are hard to exchange in D{sub 2}O further reflects the hydrophobic nature of the molecule. SP-C produced little effect on the thermotropic properties of the binary lipid mixture, as measured from acyl chain C-H and C-D stretching frequencies. However, the presence of 1 mol% protein markedly reduced the viscance and increased the elasticity of surface films, suggesting a mechanism by which SP-C facilitates the spreading of phospholipids on an aqueous surface. The possible physiological consequences of these observations are discussed.

• OSTI ID: 5822705
• Journal Information: Biochemistry; (United States), Vol. 30:41; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
PHOSPHOLIPIDS
SURFACE PROPERTIES
SURFACTANTS
INFRARED SPECTRA
CATTLE
CHOLINE
FOURIER TRANSFORMATION
HEAVY WATER
LAVAGE
LUNGS
MEMBRANES
ALCOHOLS
AMINES
AMMONIUM COMPOUNDS
ANIMALS
BODY
DOMESTIC ANIMALS
DRUGS
ESTERS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INTEGRAL TRANSFORMATIONS
LIPIDS
LIPOTROPIC FACTORS
MAMMALS
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
OXYGEN COMPOUNDS
QUATERNARY COMPOUNDS
RESPIRATORY SYSTEM
RUMINANTS
SPECTRA
TRANSFORMATIONS
VERTEBRATES
WATER
550200* - Biochemistry