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Home Biochemistry Structure and Properties of Peptides Comments

  • Question
  • The resonance structures that can be drawn for the peptide bond indicate that the peptide bond


  • Options
  • A. is stronger than an ordinary single bond
  • B. has partial double bond character
  • C. both (a) and (b)
  • D. is still not completely understood

  • Correct Answer
  • both (a) and (b) 


  • Structure and Properties of Peptides problems


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    • 1. The peptide bond in proteins is

    • Options
    • A. planar, but rotates to three preferred dihedral angles
    • B. nonpolar, but rotates to three preferred dihedral angles
    • C. nonpolar, and fixed in a trans conformation
    • D. planar, and usually found in a trans conformation
    • Discuss
    • 2. Which of the following statement is incorrect?

    • Options
    • A. Hemoglobin and myoglobin are the two oxygen binding proteins
    • B. Hemoglobin transports O2 in the blood
    • C. Myoglobin stores O2 in muscles
    • D. None of the above
    • Discuss
    • 3. The same peptide, Val-Lys-Glu-Met-Ser-Trp-Arg-Ala. was digested with chymotrypsin to produce

    • Options
    • A. Val-Lys + Glu-Met-Ser + Trp-Arg-Ala.
    • B. Val-Lys-Glu-Met-Ser-Trp + Arg-Ala.
    • C. Val-Lys-Glu-Met-Ser + Trp-Arg-Ala.
    • D. Val-Lys-Glu-Met + Ser-Trp-Arg-Ala.
    • Discuss
    • 4. In ?-pleated sheet structures neighbouring

    • Options
    • 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
    • Discuss
    • 5. In the ?-pleated sheet

    • Options
    • 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
    • Discuss
    • 6. Hydrogen bonds in a-helices are

    • Options
    • 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
    • Discuss
    • 7. The peptide bond in proteins is

    • Options
    • A. only found between proline residues
    • B. usually cis unless proline is the next amino acid
    • C. usually trans unless proline is the next amino acid
    • D. is planar because of steric hinderance
    • Discuss
    • 8. The oxygen in hemoglobin and myoglobin is bound to

    • Options
    • A. the iron atom in the heme group
    • B. the nitrogen atoms on the heme
    • C. histidine residues in the protein
    • D. lysine residues in the protein
    • Discuss
    • 9. The nature of peptide bond can be best explained as

    • Options
    • A. partial double bond
    • B. truly double bond
    • C. Hydrogen bond
    • D. Van der waals force
    • Discuss
    • 10. Peptides in the fully extended chain conformation

    • Options
    • 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
    • Discuss


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