Interaction between perdeuterated dimyristoylphosphatidylcholine and low molecular weight pulmonary surfactant protein SP-C
- Memorial Univ. of Newfoundland, St. John's (Canada)
A low molecular weight hydrophobic protein was isolated from porcine lung lavage fluid using silicic acid and Sephadex LH-20 chromatography. The protein migrated with an apparent molecular weight of 5000-6000 on SDS-PAGE under reducing and nonreducing conditions. Gels run under reducing conditions also showed a minor band migrating with a molecular weight of 12,000. Amino acid compositional analysis and sequencing data suggest that this protein preparation contains intact surfactant protein SP-C and about 30% of truncated SP-C (N-terminal leucine absent). The surfactant protein was combined with perdeuterated dimyristoylphosphatidylcholine (DMPC-d54) in multilamellar vesicles. The protein enhanced the rate of adsorption of the lipid at air-water interfaces. The ability of the protein to alter normal lipid organization was examined by using high-sensitivity differential scanning calorimetry (DSC) and 2H nuclear magnetic resonance spectroscopy (2H NMR). The calorimetric measurements indicated that the protein caused a decrease in the temperature maximum (Tm) and a broadening of the phase transition. At a protein concentration of 8% (w/w), the enthalpy change of transition was reduced to 4.4 kcal/mol compared to 6.3 kcal/mol determined for the pure lipid. NMR spectral moment studies indicated that protein had no effect on lipid chain order in the liquid-crystal phase but reduced orientational order in the gel phase. Two-phase coexistence in the presence of protein was observed over a small temperature range below the pure lipid transition temperature. Spin-lattice relaxation times (T1) were not substantially affected by the protein. Transverse relaxation time (T2e) studies suggest that the protein influences slow lipid motions.
- OSTI ID:
- 6623174
- Journal Information:
- Biochemistry; (USA), Vol. 29:24; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOLIPIDS
BIOCHEMICAL REACTION KINETICS
PROTEINS
ADSORPTION
AMINO ACID SEQUENCE
CALORIMETRY
CHROMATOGRAPHY
COMPARATIVE EVALUATIONS
DEUTERIUM
ELECTROPHORESIS
LAVAGE
LUNGS
MOLECULAR WEIGHT
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
SURFACE TENSION
SURFACTANTS
SWINE
TRACER TECHNIQUES
ANIMALS
BODY
DOMESTIC ANIMALS
ESTERS
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIPIDS
MAGNETIC RESONANCE
MAMMALS
MOLECULAR STRUCTURE
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANS
REACTION KINETICS
RESONANCE
RESPIRATORY SYSTEM
SEPARATION PROCESSES
SORPTION
SPECTRA
STABLE ISOTOPES
SURFACE PROPERTIES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques