ORGN 733 |
| Tom Measey1, Andrew Hagarman1, Fatma Eker2, Kai Griebenow3, and Reinhard Schweitzer-Stenner1. (1) Department of Chemistry, Drexel University, 32nd and Chestnut Street, Philadelphia, PA 19104, (2) Department of Biology, Drexel University, 32nd and Chestnut Streets, Philadelphia, PA 19104, (3) Department of Chemistry, University of Puerto Rico, Rio Piedras Campus, San Juan, PR 00931 |
| We measured the FTIR spectra of various XA peptides in D2O to probe the influence of side chains on the wavenumber and oscillator strength of the amide I’ band. Obtaining this information is of utmost importance for employing amide I as a tool of secondary structure analysis. GA is taken as the reference peptide owing to its negligible steric interactions with the peptide backbone. With the exception of HA, the substitution of G by sterically more demanding side chains causes a downshift of amide I’, reflecting a decrease of the CO force constant. The amide I’ band of zwitterionic GA was found at 1668 cm1-. DA, FA, RA, AA, MA, KA, YA, and EA exhibited an amide I frequency downshift of less than 6 cm-1, whereas WA, PA, VA, IA, and LA showed a frequency decrease greater than 6 cm1-. This suggests that branched aliphatic side chains cause a larger downshift. Moreover, we obtained a correlation between the wavenumber downshift and the decrease of the amide I oscillator strength. |
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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 |