ORGN 731 |
| Reinhard Schweitzer-Stenner1, Fatma Eker1, Kai Griebenow2, and Xiaolin Cao3. (1) Department of Chemistry (Schweitzer-Stenner)/Department of Biology (Eker), Drexel University, 32nd and Chestnut Streets, Philadelphia, PA 19104, (2) Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931, (3) Department of Chemistry, Syracuse University, Syracuse, NY 13244 |
| We combined FT-infrared, polarized Raman and vibrational circular dichroism measurements of the amide I’ band of alanyl-X-alanine tripeptides in D2O to obtain the dihedral angles of their central amino acid residue (X=G,V,M,H,S,P,K,L,W,Y,F). The data were analyzed by an algorithm, which exploits the excitonic coupling between the amide modes of the two peptide groups. The investigated peptides can be sorted into three classes. Valine, phenylalanine, tryptophan, histidine and serine predominantly adopt an extended β-strand conformation. Cationic lysine and proline prefer a polyproline II like structure. Methionine, glycine and leucine populate these two conformations with comparable probability. Our results are in variance with the prediction of the random coil model. We utilized the obtained structural propensities of the investigated residues and related literature information to predict the conformation of the monomeric amyloid peptide Aβ1-42 in water, which reproduces results from most recent spectroscopic studies. This demonstrates that the unfolded state of peptides can be understood in terms of the intrinsic structural propensities of its amino acid residues. |
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Proteins, Peptides, and Amino Acids
8:00 AM-12:00 PM, Thursday, August 26, 2004 Pennsylvania Convention Center -- 201A, Oral
Division of Organic Chemistry |