It is often the case that a helices are positioned in a protein such that one side faces the interior of the protein and the other, the surface of the protein. TI said to be amphiphilic helices because they face different environments. Using a helical wheel projection (shown below), which of the peptide(s) below mig an amphiphilic helix? 8 15 1 12 4 11 16 18 7 14 13 10 17 6 O SLIKSVIEMVDEWFRTFL O FLIRVLRKVFRVLTRILS

How can a protein’s potential function be determined from a protein’s primary structure? I assumed this was not possible, I thought its function was determined from its 3-dimensional structure only. Thank you for explaining this.

Draw beta sheet with backbone hydrogen bonds, is this structure on the interior or exterior of the protein and why?   Region 1: -Ser-Thr-Glu-His- Region 2: -Asp-Tyr-Lys-Asn

Within a naturally-occurring polypeptide, under neutral pH conditions (pH = 7.0), which of the following amino acids always has a negatively charged carboxyl group? the first amino acid in the primary structure histidine lysine arginine the last amino acid in the primary structure

Make a comparison between the teasons for the different flexibility that proteins that consists mainly of a beta sheet structure compared to proteins that consist mainy of alpha helices.

Which of the following is/are least likely to be found in an alpha helix because it has an inappropriate Phi angle. a   Polar charged amino acids b   Proline c   Nonpolar amino acids d   Glycine e   Polar uncharged amino acids

Peptide 1: QAMGRAGDLKYLGLHSV Peptide 2: ALMALFMVMALVLVSVLFIA Peptide 3: MVEDLLKQIARYLISE Which of these peptides would be most likely to be found as an a helix in a soluble (cytoplasmic) protein? Which would be most likely to be found as an a helix in a transmembrane protein? Which would be least likely to form an a helix of any kind? Briefly explain your answers.