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Environmental Pollutant Ozone Causes Damage to Lung Surfactant Protein B (SP-B)

DOI: 10.1021/acs.biochem.5b00308 DOI Help
PMID: 26270023 PMID Help

Authors: Joanna M. Hemming (Birkbeck, University of London) , Brian R. Hughes (Birkbeck College) , Adrian R. Rennie (Uppsala University) , Salvador Tomas (Birkbeck College) , Richard A. Campbell (Institut Laue-Langevin) , Arwel V. Hughes (Rutherford Appleton Laboratory) , Thomas Arnold (Diamond Light Source) , Stanley W. Botchway (Science and Technology Facilities Council (STFC)) , Katherine C. Thompson (Birkbeck, University of London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biochemistry , VOL 54 (33) , PAGES 5185 - 5197

State: Published (Approved)
Published: August 2015
Diamond Proposal Number(s): 7258

Open Access Open Access

Abstract: Lung surfactant protein B (SP-B) is an essential protein found in the surfactant fluid at the air–water interface of the lung. Exposure to the air pollutant ozone could potentially damage SP-B and lead to respiratory distress. We have studied two peptides, one consisting of the N-terminus of SP-B [SP-B(1–25)] and the other a construct of the N- and C-termini of SP-B [SP-B(1–25,63–78)], called SMB. Exposure to dilute levels of ozone (∼2 ppm) of monolayers of each peptide at the air–water interface leads to a rapid reaction, which is evident from an increase in the surface tension. Fluorescence experiments revealed that this increase in surface tension is accompanied by a loss of fluorescence from the tryptophan residue at the interface. Neutron and X-ray reflectivity experiments show that, in contrast to suggestions in the literature, the peptides are not solubilized upon oxidation but rather remain at the interface with little change in their hydration. Analysis of the product material reveals that no cleavage of the peptides occurs, but a more hydrophobic product is slowly formed together with an increased level of oligomerization. We attributed this to partial unfolding of the peptides. Experiments conducted in the presence of phospholipids reveal that the presence of the lipids does not prevent oxidation of the peptides. Our results strongly suggest that exposure to low levels of ozone gas will damage SP-B, leading to a change in its structure. The implication is that the oxidized protein will be impaired in its ability to interact at the air–water interface with negatively charged phosphoglycerol lipids, thus compromising what is thought to be its main biological function.

Subject Areas: Biology and Bio-materials, Chemistry, Environment

Instruments: I07-Surface & interface diffraction

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