BCH210H1 Midterm: Study notes for midterm

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redtermite204

21 Dec 2011

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BCH210H1 Full Course Notes

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3 types phi = angle around the n-alpha c bond psi = angle around the alpha c-c=o bond omega = angle around the c-n bond chi angles reserved for side chain rotation. *** alpha helix: (phi, psi) = (-60 degrees, -50 degrees) *** beta sheet: (phi, psi) = (-140 degrees, +135 degrees) *** polyproline helix: (phi, psi) = (-60 degrees, +135 degrees) L-residues in proteins has 25% (phi, psi) space normally populated: ex. When stretched, intra-helix hydrogen bonds can be broken and inter-strand hydrogen bonds form via alpha-helix to beta-sheet transition sulfur present => disulfide crosslinks help restore to original shape. Resonance structures give c-n bond partial double-bond character. Peptide bond = resonance hybrid of two extremes, thus bond is planar: partial double-bond character, dihedral angle omega fixed, planar and trans. Inter-chain hydrogen bonds formed while side chains are above and below the plane of the hydrogen-bond network. Strong fibres that resist tension via covalent bonds also collagen.

Related Questions

Match the protein to the descriptions.

The protein to consider here is collagen.

There may be several answers for some of these. Select all that apply.

		contains intrachain hydrogen bonds
		contains heptad repeats
		contains Glycine at every 3^rd residue
		contains hydroxyproline
		contains left-handed helices
		contains interchain hydrogen bonds
		every second residue is Gly

lavendercamel652

1. The level of protein structure that is stabilized primarilyby non-covalent interactions between the side chains within asingle polypeptide chain is refered to as its:

A) primary structure

B) secondary structure

C) tertiary structure

D) quaternary structure

E) none of the above

2. Collagen, a strong fibrous protein found in connectivetissue, bone, and the extracellular matrix, has a structure inwhich three left-handed helices wind around each other to form aright-handed triple helix. The primary structure of collagen has arepeat unit of -(Gly-X-Pro)- Which of the following bonds stabilizethe collagen triple helix? (mark all that apply)

A) Hydrogen bonds between hydroxyproline residues

B) Hydrogen bonds between N-H and C=O

C) Ionic bonds between amino acid side chains

D) Hydrogen bonds between charged amino acids

3. The non-covalent forces that stabilize the Beta-strandconformation of peptides include:

A) H-bonds between amide C=O and amide NH

B) Van der Waals packing between the peptide backbone atoms

C) Van der Waals packing due to side chain interdigitation

D) Only A and B above

E) None of the above

4. What is the approximate length difference of a 22-kDasingle-stranded ?-helical protein segment vs. a 22-kDasingle-stranded ?-strand protein segment? Assume a mean residuemass of 110 Da. Show work.

5. Circular dichroism measurements have shown that the peptidebackbone of poly-l-lysine (KKKKKKK) adopts a random coilconformation at pH 7.0, but becomes ?-helical as the pH is raisedabove 10. This observation is known as the

magentaotter572

The carbon-nitrogen peptide bond is rigid, but rotation can take place about the...

BCH210H1 Midterm: Study notes for midterm

BCH210H1 Full Course Notes

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