Multiple Choice
Which of the following is true regarding the α-helices in the protein bacteriorhodopsin?
4. Protein Structure
Alpha Helix
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Which of the following statements about α-helices is false?
A
Alpha helices of the Ribonuclease A enzyme are stabilized by hydrogen bonding of the peptide backbone.
B
Hemoglobin proteins predominantly contain left-handed α-helices.
C
The R groups of amino acids residues in an α-helix extend radially outward (away from helix center).
D
α-helix hydrogen bonds of the enzyme citrate synthase are roughly parallel to the axis of the α-helix.
Verified step by step guidance1
Understand the structure of an α-helix: It is a common secondary structure in proteins, characterized by a right-handed coil where the backbone is stabilized by hydrogen bonds.
Recall that in an α-helix, the hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of another amino acid four residues away, creating a stable helical structure.
Recognize that α-helices are typically right-handed, meaning they twist in a clockwise direction when viewed from the N-terminus to the C-terminus. Left-handed α-helices are rare in natural proteins.
Consider the role of R groups (side chains) in an α-helix: They extend outward from the helical axis, allowing them to interact with the surrounding environment and other molecules.
Evaluate the given statements: The statement about hemoglobin proteins predominantly containing left-handed α-helices is false, as hemoglobin primarily contains right-handed α-helices, consistent with the common structure of α-helices in proteins.
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