Myoglobin was the first globular protein whose structure was solved by X-ray crystallography. The protein contains a hydrophobic core formed by the sides of several α-helices. For human myoglobin, the sequence of helix E is: SEDLKKHGATVLTALGGIL. For this helix, construct a helical wheel plot and label the hydrophobic residues likely to contribute to the hydrophobic core.
Added by Abigail S.
Step 1
First, we need to identify the hydrophobic residues in the given sequence. Hydrophobic residues are: A, V, I, L, M, F, Y, W, and P. Show more…
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Myoglobin is made up of eight alpha helices. One of these helices is on the surface of myoglobin and interacts with both the protein core and the aqueous solvent. It has the following sequence: QGAMNKALEHFRKDIAA. Using the helical wheel below for guidance, draw a helical diagram that maps the positions of the side chains on the myoglobin helix. Circle the face of this helix that is likely exposed to the hydrophobic protein core. Draw a box around the face that is likely exposed to the surrounding aqueous environment. Explain your reasoning in one sentence. For each of the following mutations where a native residue is replaced by the indicated residue, predict whether the mutation will stabilize or destabilize the helix. Explain your reasoning for each in one sentence: Leu8 -> Pro, Glu9 -> Arg, Phe11 -> Lys (Hint: consider your answer to part b).
Adi S.
This is an illustration of the protein myoglobin. It is composed of one chain of amino acids, folded up. What can be said about its structure? (Mark all correct answers) - The entire molecule is an example of secondary structure. - The entire molecule is an example of tertiary structure. - The shape will be the same for every myoglobin molecule the cell makes. - The shape will be different for the next myoglobin molecule the cell makes. - The molecule contains secondary structures in the form of alpha helices.
Riaz A.
Myoglobin contains eight α helices, one of which has the following sequence: –Gln–Gly–Ala–Met–Asn–Lys–Ala–Leu–Glu–His–Phe–Arg–Lys–Asp–Ile–Ala–Ala– Which side chains are likely to be on the side of the helix that faces the interior of the protein? Which are likely to be facing the aqueous solvent? Explain your answers.
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