sapling learning eratin is an intermediate filament with a basic structural unit
ID: 51803 • Letter: S
Question
sapling learning eratin is an intermediate filament with a basic structural unit of two a helices in a coiled coil. Each helix as a seven residue repeating unit (heptad repeat). A representation looking down the a helices of a coiled coil dimer is shown below. Each letter represents a different amino acid residue. Identify the three true statements about the structure of keratin. Click here to view a table of the amino acids. a Keratin is rich in Cys residues, enabling the formation of covalent cross-links between peptide chains and increasing the strength of the protein. V Val-Asp-Glu-Ala-Glu-His-His is a likely repeat in the a helix of keratin. The a helix of the coiled coil is wound less tightly than predicted for an a helix. Each polypeptide in the dimer has 3.6 residues per turn, and a nonpolar group occurs every 3.5 residues, resulting in a slight winding, or twist, around the other polypeptide, forming a colled Coll The residues at positions b and c are less likely to be polar or charged because they are in contact with the solvent. His-Ala-His-Glu-His-Asp-Asp is a likely repeat in the a helix of keratin. Keratin molecules are very strong due to hydrophilic interactions between charged amino acid side chains.Explanation / Answer
The following 3 statements are true
1. alpha keratin is rich in Cys residues........strength of protein
2. Val-Asp-Glu-Ala-Glu-His-His is a likely repeat in the helix of alpha- keratin
3. Each polypeptide in a dimer has 3.6 residues per turn............forming a coiled coil.
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