Exam 1 Session 4

Question 0

Cis proline:: Secondary structure:: Proline creates a bend in the backbone of alpha helices because of it’s ____ structure. It cannot fit into a helix because of 2 reasons. Rotation around the bond between the ______ and the alpha carbon is severely restricted. Prolines alpha amino group cannot participate in intrachain ____ bonding.

Answer 0

Cyclic Nitrogen Hydrogen

Question 1

B barrel arrangements?

Answer 1

Exist- that’s really all you have to know about them.

Question 2

Post translational isomerization of ___ proline to ___proline introduces a turn. The upstream residue in most instances is a ____ which has a ____ for it’s R group that can easily fit into the turn and accommodate the steric constraint imposed by cis proline. The lack of freedom of rotation around neither the peptide bond of the upstream or down stream? Amino acid or the ring causes the ring to be rigid and planar. This stabilizes the turn.

Answer 2

Trans Cis Glycin H Downstream

Question 3

Proline cannot conform to an alpha helix because of ____. It is in a curved structure because of the ____ of the molecule (ie. the ring in it’s structure causes the turn).

Answer 3

Steric hinderance Geometry

Question 4

All turns in secondary structure are caused by proline? T or F?

Answer 4

False

Question 5

All cis Prolines cause turns in secondary structure? T or F?

Answer 5

True

Question 6

Because of the side chain of proline is covalently bound to the amino nitrogen, the amino nitrogen can no longer ____ to anything else. This is a electrical/ stereochemical/ chemical problem.

Answer 6

H-bond

Question 7

Tertiary stucture

Tertiary stucture is 3D folding of polypeptide chain

B)Stuctural stability is conferred by?

C) ______ R groups are oriented inward to form a hydrophobic core, similiar to oil in water.

D) when folded in the right way ____ residues can form a _____ because of the thiol groups in their side chains.

Answer 7

Covalent Bonds

Ionic Bonds

Van der Waals Forces

Hydrophobic interactions

C) Nonpolar

D) Cysteine, disulfide bridge

Question 8

Quaternary Structure

A) quaternary structure refers to how individual polypeptide chains of oligomeric globular proteins are clustered together.

B) stuctural stability is conferred by?

Answer 8

B) hydrophobic interactions, van der waals forces, ionic bonds, and hydrogen bonds

Question 9

____ is the loss of biologiocal activity as a result of loss of native conformation

Answer 9

Denaturation