1DFW

CONFORMATIONAL MAPPING OF THE N-TERMINAL SEGMENT OF SURFACTANT PROTEIN B IN LIPID USING 13C-ENHANCED FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR)

Summary for 1DFW

• Entry DOI: 10.2210/pdb1dfw/pdb
• Descriptor: LUNG SURFACTANT PROTEIN B (1 entity in total)
• Functional Keywords: lung surfactant protein, saposin, immune system
• Total number of polymer chains: 1
• Total formula weight: 2932.70

Authors

Gordon, L.M.,Lee, K.Y.C.,Lipp, M.M.,Zasadzinski, J.A.,Walther, F.J.,Sherman, M.A.,Waring, A.J. (deposition date: 1999-11-22, release date: 1999-12-10, Last modification date: 2024-02-07)

Primary citation

Gordon, L.M.,Lee, K.Y.,Lipp, M.M.,Zasadzinski, J.A.,Walther, F.J.,Sherman, M.A.,Waring, A.J.
Conformational mapping of the N-terminal segment of surfactant protein B in lipid using 13C-enhanced Fourier transform infrared spectroscopy.
J.Pept.Res., 55:330-347, 2000

PubMed Abstract: Synthetic peptides based on the N-terminal domain of human surfactant protein B (SP-B1-25; 25 amino acid residues; NH2-FPIPLPYCWLCRALIKRIQAMIPKG) retain important lung activities of the full-length, 79-residue protein. Here, we used physical techniques to examine the secondary conformation of SP-B1-25 in aqueous, lipid and structure-promoting environments. Circular dichroism and conventional, 12C-Fourier transform infrared (FTIR) spectroscopy each indicated a predominate alpha-helical conformation for SP-B1-25 in phosphate-buffered saline, liposomes of 1-palmitoyl-2-oleoyl phosphatidylglycerol and the structure-promoting solvent hexafluoroisopropanol; FTIR spectra also showed significant beta- and random conformations for peptide in these three environments. In further experiments designed to map secondary structure to specific residues, isotope-enhanced FTIR spectroscopy was performed with 1-palmitoyl-2-oleoyl phosphatidylglycerol liposomes and a suite of SP-B1-25 peptides labeled with 13C-carbonyl groups at either single or multiple sites. Combining these 13C-enhanced FTIR results with energy minimizations and molecular simulations indicated the following model for SP-B1-25 in 1-palmitoyl-2-oleoyl phosphatidylglycerol: beta-sheet (residues 1-6), alpha-helix (residues 8-22) and random (residues 23-25) conformations. Analogous structural motifs are observed in the corresponding homologous N-terminal regions of several proteins that also share the 'saposin-like' (i.e. 5-helix bundle) folding pattern of full-length, human SP-B. In future studies, 13C-enhanced FTIR spectroscopy and energy minimizations may be of general use in defining backbone conformations at amino acid resolution, particularly for peptides or proteins in membrane environments.

PubMed: 10798379
DOI: 10.1034/j.1399-3011.2000.00693.x

Experimental method

INFRARED SPECTROSCOPY