Location of Structural Transitions in an Isotopically Labeled Lung Surfactant SP-B Peptide by IRRAS
| Autor: | Darline Dieudonné, Richard Mendelsohn, Peng Cai, Joseph W. Brauner, Kevin M. W. Keough, Carol R. Flach, June Stewart |
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| Rok vydání: | 2003 |
| Předmět: |
Models
Molecular Conformational change Spectrophotometry Infrared Protein Conformation Molecular Sequence Data Biophysics Peptide 010402 general chemistry 01 natural sciences Phase Transition Isotopic labeling Structure-Activity Relationship 03 medical and health sciences Protein structure Species Specificity Pulmonary surfactant Monolayer Animals Humans Surface Tension Organic chemistry Computer Simulation Pulmonary surfactant-associated protein B Amino Acid Sequence Peptide sequence Myelin Sheath 030304 developmental biology chemistry.chemical_classification Biological Products 0303 health sciences Membranes Crystallography Pulmonary Surfactant-Associated Protein B Chemistry Proteins Pulmonary Surfactants Rats 0104 chemical sciences Isotope Labeling Swine Miniature |
| Zdroj: | Biophysical Journal. 85:340-349 |
| ISSN: | 0006-3495 |
| DOI: | 10.1016/s0006-3495(03)74478-6 |
| Popis: | Pulmonary surfactant, a lipid/protein complex that lines the air/water interface in the mammalian lung, functions to reduce the work of breathing. Surfactant protein B (SP-B) is a small, hydrophobic protein that is an essential component of this mixture. Structure-function relationships of SP-B are currently under investigation as the protein and its peptide analogs are being incorporated into surfactant replacement therapies. Knowledge of the structure of SP-B and its related peptides in bulk and monolayer phases will facilitate the design of later generation therapeutic agents. Prior infrared reflection-absorption spectroscopic studies reported notable, reversible surface pressure-induced antiparallel beta-sheet formation in a synthetic peptide derived from human SP-B, residues 9-36 (SP-B(9-36)). In the current work, infrared reflection-absorption spectroscopy is applied in conjunction with isotopic labeling to detect the site and pressure dependence of the conformational change. SP-B(9-36), synthesized with (13)C=O-labeled Ala residues in positions 26, 28, 30, and 32, shifted the beta-sheet marker band to approximately 1600 cm(-1) and thus immediately identified this structural element within the labeled region. Surface pressure-induced alterations in the relative intensities of Amide I band constituents are interpreted using a semiempirical transition dipole coupling model. In addition, electron micrographs reveal the formation of tubular myelin structures from in vitro preparations using SP-B(9-36) in place of porcine SP-B indicating that the peptide has the potential to mimic this property of the native protein. |
| Databáze: | OpenAIRE |
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