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Protein Folding and Denaturation

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Questions and Answers

What is the central metal ion in the heme molecule?

Mg2+
Zn2+
Fe2+ (correct)
Ca2+

What is the function of the heme group in hemoglobin and myoglobin?

To stabilize the polypeptide chain
To reversibly bind oxygen (correct)
To facilitate protein denaturation
To catalyze peptide bond formation

What is the prosthetic group tightly bound to hem proteins?

NAD+
Heme (correct)
FAD
Coenzyme A

What is the structure of myoglobin?

A compact molecule with α-helix stretches (B) Signup and view all the answers

What is the function of myoglobin?

To function as a reservoir for oxygen (C) Signup and view all the answers

What is the coordination of the heme Fe++?

One bond to the side chain of a histidine residue and one available to bind oxygen (C) Signup and view all the answers

What is the central element of the porphyrin ring in myoglobin?

Iron (B) Signup and view all the answers

What is the function of the distal histidine in myoglobin?

Helps stabilize the binding of oxygen (B) Signup and view all the answers

What is the structure of hemoglobin A?

Four polypeptide chains: two α chains and two β chains (B) Signup and view all the answers

What is the difference between the T form and the R form of hemoglobin?

T form has low oxygen affinity, R form has high oxygen affinity (D) Signup and view all the answers

What is the significance of the oxygen dissociation curve for myoglobin?

It shows a hyperbolic shape (D) Signup and view all the answers

What is the difference between the oxygen binding affinity of myoglobin and hemoglobin?

Myoglobin has higher oxygen binding affinity than hemoglobin (A) Signup and view all the answers

Which type of bond stabilizes the α-helix?

Intra chain hydrogen bonds (A) Signup and view all the answers

What is the characteristic feature of a β-sheet?

Segments of polypeptide chains running alongside each other (B) Signup and view all the answers

In a β-sheet, what type of bonds are formed between different segments of polypeptide?

Hydrogen bonds (A) Signup and view all the answers

What is the name given to a simple structural motif involving β-sheets?

β-Bend (β-hairpin) (A) Signup and view all the answers

In an antiparallel β-sheet, what is the arrangement of the N-terminal and C-terminal ends of the β-strands?

They are alternating (A) Signup and view all the answers

What is the typical composition of a β-Bend?

Four amino acids, including proline and glycine (A) Signup and view all the answers

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