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1spf
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(New page: 200px<br /><applet load="1spf" size="450" color="white" frame="true" align="right" spinBox="true" caption="1spf" /> '''THE NMR STRUCTURE OF THE PULMONARY SURFACTAN...)
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Revision as of 00:25, 21 November 2007
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THE NMR STRUCTURE OF THE PULMONARY SURFACTANT-ASSOCIATED POLYPEPTIDE SP-C IN AN APOLAR SOLVENT CONTAINS A VALYL-RICH ALPHA-HELIX
Overview
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.
About this Structure
1SPF is a Single protein structure of sequence from Sus scrofa. Full crystallographic information is available from OCA.
Reference
The NMR structure of the pulmonary surfactant-associated polypeptide SP-C in an apolar solvent contains a valyl-rich alpha-helix., Johansson J, Szyperski T, Curstedt T, Wuthrich K, Biochemistry. 1994 May 17;33(19):6015-23. PMID:8180229
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