Structure and Properties of Peptides

Question: In deoxy hemoglobin (Hb), the Fe (II) is coordinated to
[A].

four nitrogens of heme, the proximal His, and a water molecule

[B].

four nitrogens of heme and to a water molecule

[C].

two nitrogens of heme and to three His residues in Hb

[D].

two nitrogens of heme and to three water molecules

Answer: Option A

Explanation:

No answer description available for this question.

Question: Heme is the binding pocket of myoglobin and hemoglobin and is composed of
[A].

negatively charged residues

[B].

polar residues

[C].

hydrophobic residues

[D].

positively charged residues

Answer: Option C

Explanation:

No answer description available for this question.

Question: Hydrogen bonds in a-helices are
[A].

more numerous than Vander Waals interactions

[B].

not present at Phe residues

[C].

analogous to the steps in a spiral staircase

[D].

roughly parallel to the helix axis

Answer: Option D

Explanation:

No answer description available for this question.

Question: Peptides in the fully extended chain conformation
[A].

have Y = F = 180°

[B].

do not occur in nature

[C].

also have a cis geometry in their peptide bonds

[D].

are equivalent to the (3-sheet structure

Answer: Option A

Explanation:

No answer description available for this question.

Question: If the F and Y angles of each peptide unit in a protein are known, which of the following may also be determined?
[A].

Complete secondary structure

[B].

Complete tertiary structure

[C].

Complete quaternary structure

[D].

Thermodynamic stability

Answer: Option A

Explanation:

No answer description available for this question.

Question: In β-pleated sheet structures neighbouring
[A].

chains lie in a flat plane

[B].

neighboring residues are hydrogen bonded

[C].

neighboring chains are connected by a-helices

[D].

neighboring chains are hydrogen bonded

Answer: Option D

Explanation:

No answer description available for this question.

Question: Hemoglobin has quaternary structure and is made up of
[A].

six polypeptide chains, two α-chains and four β-chains

[B].

two polypeptide chains, one α-chains and one β-chains

[C].

four polypeptide chains, two α-chains and two β-chains

[D].

five polypeptide chains, two α-chains and three β-chains

Answer: Option C

Explanation:

No answer description available for this question.

Question: In the β-pleated sheet
[A].

hydrogen bonds are formed between the peptide bonds

[B].

adjacent polypeptide chains can either be parallel or antiparallel

[C].

the polypeptide chain is fully extended

[D].

all of the above

Answer: Option D

Explanation:

No answer description available for this question.

Question: Which of the following statements is incorrect?
[A].

Protein G contains both a-helix and P-sheet

[B].

Protein G contains only a-helix

[C].

Fatty acid binding protein contains largely P-sheet

[D].

Hemoglobin contains four sub-units

Answer: Option B

Explanation:

No answer description available for this question.

Question: Disulfide bonds most often stabilize the native structure of
[A].

extracellular proteins

[B].

dimeric proteins

[C].

hydrophobic proteins

[D].

intracellular proteins

Answer: Option A

Explanation:

No answer description available for this question.