5 the unfolding of the α helix of a polypeptide to a

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bonds per second) to account for the observed yearly growth of hair. 5. The unfolding of the α helix of a polypeptide to a randomly coiled conformation is accompanied by a large decrease in a property called specific rotation, a measure of a solution’s capacity to rotate plane-polarized light. Polyglutamate, a polypeptide made up of only L -Glu residues, has the α -helical conformation at pH 3. When the pH is raised to 7, there is a large decrease in the specific rotation of the solution. Similarly, polylysine ( L -Lys residues) is an α helix at pH 10, but when the pH is lowered to 7 the specific rotation also decreases, as shown by the following graph. What is the explanation for the effect of the pH changes on the conformations?
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6. Our growing understanding of how proteins fold allows researchers to make predictions about protein structure based on primary amino acid sequence data. Consider the following amino acid sequence. (a) Where might bends or b turns occur? (b) Where might disulfide cross-linkages be formed? (c) Assuming that this sequence is part of a larger globular protein, indicate the probable location (the external surface or interior of the protein) of the following amino acid residues: Asp, Ile, Thr, Ala, Gln, Lys. Explain your reasoning. (Hint: See the hydrophobicity scale from MoL
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  • Winter '10
  • HarryNoller
  • amino acid sequence

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