Please Answer Clearly & Thouroghly Keratin is an intermediate filament with a ba
ID: 54147 • Letter: P
Question
Please Answer Clearly & Thouroghly
Keratin is an intermediate filament with a basic structural unit of two alpha helices in a coiled coil. Each helix has a seven residue repeating unit (heptad repeat). A representation looking down the alpha helices of a coiled coil dimer is shown below. Each letter represents a different amino acid residue. Identify the true statements about the structure of keratin. Click here to view a table of the amino acids. The consequence of the coiled coil is that each alpha-helix in the dimer is wound tighter, has a smaller rise per turn, and twists around the other polypeptide. The residues at positions b and c are less likely to be polar or charged because they are in contact with the solvent. Keratin molecules are very strong due to hydrophilic interactions between charged amino acid side chains. Va -Asp-Glu-Gly-Cys-His-Ser is a likely repeat in the alpha helix of keratin. The N-terminus of one alpha helix is aligned with the C-terminus of the other a helix in the dimer. His-Gly-Ser-Cys-Ser-Asp-Thr is a likely repeat in the alpha helix of keratin.Explanation / Answer
Val-Asp-Glu-Gly-Cys-His-Ser is a likely repeat of the alpha helix of keratin.
The primary structure of the protein reveals that the heptad repeat has the pattern of NXXNXXX, where N represent a hydrophobic amino acid and X represent a hydrophilic amino acid. The above answer best suits the pattern. Valine and glycine are hydrophobic amino acids, remaining others are hydrophilic amino acids.