ORGN 730 |
| Neal J. Zondlo, Krista M. Thomas, and Alaina M. Brown. Department of Chemistry and Biochemistry, University of Delaware, 206 Lammot DuPont Laboratories, Newark, DE 19716 |
| Polyproline helix (PPII) is a major conformation in protein-protein interfaces and has been proposed as a dominant conformation in proline-rich domains. We synthesized and analyzed a series of model peptides (Ac-GPPXPPGY-NH2) to experimentally determine the propensities of amino acids for PPII. We found proline and leucine to most strongly favor PPII. Three classes of residues disfavored PPII: beta-branched residues, residues with short polar sidechains, and aromatic residues. NMR revealed that the basis of low PPII propensity for aromatic residues was amide cis-trans isomerism, with aromatic residues displaying high percentages (30-60%) of species with cis amide bonds. We synthesized a series of peptides with electron-rich and electron-poor aromatic residues preceding proline. We find, in proline-rich peptides and model tetrapeptides, that electron-poor residues preceding proline display little cis amide conformation and support PPII, whereas more electron-rich aromatic residues strongly favor cis amide bond formation and can support type VI beta turn formation. |
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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 |