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1erf
From Proteopedia
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(New page: 200px<br /> <applet load="1erf" size="450" color="white" frame="true" align="right" spinBox="true" caption="1erf" /> '''CONFORMATIONAL MAPPING OF THE N-TERMINAL FU...)
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Revision as of 11:55, 8 November 2007
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CONFORMATIONAL MAPPING OF THE N-TERMINAL FUSION PEPTIDE OF HIV-1 GP41 USING 13C-ENHANCED FOURIER TRANSFORM INFRARED SPECTROSCOPY (FTIR)
Overview
The N-terminal domain of HIV-1 glycoprotein 41000 (FP; residues 1--23;, AVGIGALFLGFLGAAGSTMGARSCONH(2)) participates in fusion processes, underlying virus--cell infection. Here, we use physical techniques to, study the secondary conformation of synthetic FP in aqueous, structure-promoting, lipid and biomembrane environments. Circular, dichroism and conventional, (12)C-Fourier transform infrared (FTIR), spectroscopy indicated the following alpha-helical levels for FP in, 1-palmitoyl-2-oleoylphosphatidylglycerol (POPG), liposomes-hexafluoroisopropanol (HFIP)>trifluoroethanol, (TFE)>phosphate-buffered saline (PBS). (12)C-FTIR spectra also showed, disordered FP structures in these environments, along with substantial, beta-structures for FP in TFE or PBS. In further experiments designed to, map secondary conformations to specific residues, isotope-enhanced FTIR, spectroscopy was performed using a suite of FP peptides labeled with, (13)C-carbonyl at multiple sites. Combining these (13)C-enhanced FTIR, results with molecular simulations indicated the following model for FP in, HFIP: alpha-helix (residues 3-16) and random and beta-structures (residues, 1-2 and residues 17-23). Additional (13)C-FTIR analysis indicated a, similar conformation for FP in POPG at low peptide loading, except that, the alpha-helix extends over residues 1-16. At low peptide loading in, either human erythrocyte ghosts or lipid extracts from ghosts, (13)C-FTIR, spectroscopy showed alpha-helical conformations for the central core of FP, (residues 5-15); on the other hand, at high peptide loading in ghosts or, lipid extracts, the central core of FP assumed an antiparallel, beta-structure. FP at low loading in ghosts probably inserts deeply as an, alpha-helix into the hydrophobic membrane bilayer, while at higher loading, FP primarily associates with ghosts as an aqueous-accessible, beta-sheet., In future studies, (13)C-FTIR spectroscopy may yield residue-specific, conformations for other membrane-bound proteins or peptides, which have, been difficult to analyze with more standard methodologies.
About this Structure
1ERF is a Single protein structure of sequence from [1] with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
Conformational mapping of the N-terminal peptide of HIV-1 gp41 in membrane environments using (13)C-enhanced Fourier transform infrared spectroscopy., Gordon LM, Mobley PW, Pilpa R, Sherman MA, Waring AJ, Biochim Biophys Acta. 2002 Feb 15;1559(2):96-120. PMID:11853678
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