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.


I - A - H - T- Y- G - P - F- G - A - A- M - C - K - W - E - A- Q - P - D – G – M - E - C- A - F - H - R


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28


(a) Where might bends or b turns occur? Why? Draw the provided amino acid sequence in the bent form (use the single letter abbreviation; don’t have to draw the structure of each amino acid).


(b) Draw the full structure amino acid(s) that cause bends and use your drawing to explain why bends occur.


(c) Where might intrachain disulfide cross-linkages be formed? Indicate in your drawing the location of the disulfide cross-linkages.


(d) 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.


(e) Look at your drawing and predict what would be different if amino acid 13 is changed to F. Would this change affect the stability of the protein? Explain your reasoning