1SPF

THE NMR STRUCTURE OF THE PULMONARY SURFACTANT-ASSOCIATED POLYPEPTIDE SP-C IN AN APOLAR SOLVENT CONTAINS A VALYL-RICH ALPHA-HELIX

Summary for 1SPF

• Entry DOI: 10.2210/pdb1spf/pdb
• Descriptor: PULMONARY SURFACTANT-ASSOCIATED POLYPEPTIDE C (1 entity in total)
• Functional Keywords: lipoprotein(surface film)
• Biological source: Sus scrofa (pig)
• Cellular location: Secreted, extracellular space, surface film: P15785
• Total number of polymer chains: 1
• Total formula weight: 3712.86

Authors

Johansson, J.,Szyperski, T.,Curstedt, T.,Wuthrich, K. (deposition date: 1994-09-26, release date: 1994-12-20, Last modification date: 2024-05-22)

Primary citation

Johansson, J.,Szyperski, T.,Curstedt, T.,Wuthrich, K.
The NMR structure of the pulmonary surfactant-associated polypeptide SP-C in an apolar solvent contains a valyl-rich alpha-helix.
Biochemistry, 33:6015-6023, 1994

PubMed Abstract: The nuclear magnetic resonance (NMR) structure of the pulmonary surfactant-associated lipoplypeptide C (SP-C) was determined in a mixed solvent of C2H3Cl/C2H3OH/ 1 M HCl 32:64:5 (v/v). Sequence-specific 1H NMR assignments and the collection of conformational constraints were achieved with two-dimensional 1H NMR, and the structure was calculated with the distance geometry program DIANA. The root mean square deviations for the well-defined polypeptide segment of residues 9-34 calculated for the 20 best energy-minimized DIANA conformers relative to their mean are 0.5 and 1.3 A for the polypeptide backbone atoms N, C alpha, and C', and for all heavy atoms, respectively. The 35-residue polypeptide chain of SP-C forms an alpha-helix between positions 9 and 34, which includes two segments of seven and four consecutive valyls that are separated by a single leucyl residue. The N-terminal hexapeptide segment, which includes two palmitoylcysteinyls, is flexibly disordered. The length of the alpha-helix is about 37 A, and the helical segment of residues 13-28, which contains exclusively aliphatic residues with branched side chains, is 23-A long and about 10 A in diameter. The alpha-helix is outstandingly regular, with virtually identical chi 1 angles for all valyl residues. The observation of a helical structure of SP-C was rather unexpected, considering that Val is generally underrepresented in alpha-helices, and it provides intriguing novel insights into the structural basis of SP-C functions as well as into general structural aspects of protein-lipid interactions in biological membranes.

PubMed: 8180229
DOI: 10.1021/bi00185a042

Experimental method

SOLUTION NMR