Protein Structure- Keagan (week 3)

Question 1

Peptide bond
Characteristics

Answer 1

Forms from dehydrtartion rxn between two AA

-partial double bond character
-rigid and planar
- trans configuration
- uncharged but polar(potential to form H-bond)

Question 2

Determination of primary structure

Answer 2

1. Acid hydrolysis- cleaves peptide bonds
   Chromatography- separates AA based on charge
2. Peptide sequencing from N-terminal (demand reagent)
3. DNA sequencing

Question 3

Secondary structures

Answer 3

A-helix
B-sheet
B-turn
Loop

HYDROGEN BONDS STABALIZE these structures

Question 4

Intracranial hydrogen bond

Answer 4

Maintain a-helix structure

Question 5

Alpha helix- disrupted by

Answer 5

1. Proline, glycine
2. Large numbers of charges AA
3. AA with bulky R group

3.6 residues per turn
R groups extend outward

Question 6

Beta sheet

Answer 6

All peptide bond components involve H-bonds
Parallel or antiparallel

Question 7

Two beta sheet neurological disorders

Answer 7

Alzheimer’s Disease- aggregation of amyloid protein (cleavage of b-secretes and y-secretase)

Huntington disease- aggregation of polyglutamine b-strands of Huntington protein

Question 8

Beta turn

Answer 8

Often include charged residues
Stabilized by H-bonds

Usually 4 AA with PROLINE, GLYCINE

Question 9

Two classes of tertiary structure

Answer 9

Globular proteins- enzymes, transporters

Fibrous proteins- collagen, elastin, keratin

Question 10

Forces involved in maintaining tertiary structure

Answer 10

Hydrogen bonds
Disulfide bonds
Hydrophobic interactions
Electrostatic interactions

Question 11

Protein denaturation lose what structure

Answer 11

Tertiary structure

Question 12

Quaternary structure held together by what

Answer 12

Noncovalent interactions
-h-bonds
-hydrophobic interactions
-electrostatic interactions