ORGN 387 |
| Proline-rich domains are among the most common domains in eukaryotes and play critical roles in cell signaling. We have used CD and NMR to determine the conformational preferences of residues in proline-rich sequences. We synthesized and analyzed a series of model peptides (Ac-GPPXPPGY-NH2) to experimentally determine the propensities of amino acids for polyproline helix (PPII). We found proline and leucine to most strongly favor PPII, although most residues supported significant PPII. Three classes of residues disfavored PPII: beta-branched residues, residues with short polar sidechains, and aromatic residues. Unnatural amino acids were incorporated to determine the bases for PPII propensities. PPII propensities were similar in the less proline-rich context GPXPXPGY. NMR revealed that the basis of low PPII propensities for aromatic residues was amide cis-trans isomerism. Electron-poor aromatic residues preceding proline display little cis amide conformation and support PPII, whereas more electron-rich aromatic residues strongly favor cis amide bond formation. |
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Proteins, Peptides, Amino Acids, and Enzymes
8:00 AM-11:40 AM, Tuesday, 15 March 2005 Convention Center -- Room 9, Oral
Division of Organic Chemistry |