Proteins

Question 1

Questions

Answer 1

Answers

Question 2

Asp

Answer 2

4

Question 3

Glu

Answer 3

4

Question 4

His

Answer 4

6

Question 5

Cys

Answer 5

8.4

Question 6

Tyr

Answer 6

10.5

Question 7

Lys

Answer 7

10.5

Question 8

Arg

Answer 8

12.5

Question 9

carboxylate

Answer 9

2.2

Question 10

amino

Answer 10

9

Question 11

Primary

Answer 11

AA sequence

Question 12

Secondary

Answer 12

H-bonds. alpha-helix, beta-sheet, beta-turn

Question 13

Teritiary

Answer 13

Folding of secondary structures. Folded forces (hydrophobic, H bonding, van der waals, electrostatic)

Question 14

Quaternary

Answer 14

2 or more subunits. Can exhibit coopertivity. Entropy favors unfolded state

Question 15

K(f)

Answer 15

[folded protein]/[unfolded protein]

Question 16

Oxygen

Answer 16

Limited solubility

Question 17

Myoglobin

Answer 17

Function: Store oxygen in muscle for release during O2 deprevation. Structure: Monometric protein with heme. Noncooperative. O2 binding independent of pH, CO2, 2,3 BPG

Question 18

Hemoglobin

Answer 18

Function: Carry O2 from lungs to tissues, alsotransport CO2 and H+. Structure: 2 alpha, 2 beta units with hemes, nonpolar residues (His) protect Fe2+ oxidation to Fe3+ (does not bind O2), bent O2 binding favored (CO2 want to be linear). O2 affinity dependent on pH, CO2, and 2,3 BPG

Question 19

Globin pocket

Answer 19

Hydrophobic interior (protect Fe2+ from oxidation), polar exterior (increases solubility of Hb)

Question 20

Hb (fetal)

Answer 20

Ser replaces His so O2 binds HbF tighter than HbA due to HbF decreased affinity for BPG (via loss of His)

Question 21

BPG

Answer 21

Binds Hb and reduces its affinity for O2 by stabilizing T-form. High altitude increase [BPG].

Question 22

Oxygenation of Hb

Answer 22

Pulls heme into plane and stabilizes R state

Question 23

Bohr effect

Answer 23

Lowering pH, increasing [H+], increasing [CO2], causes Hb to release more O2. Opposite occurs in lungs where high [O2] causes Hb to release H+ and CO2

Question 24

Carbamino-Hb

Answer 24

N-terminal residue of deoxyHb reacts with CO2 forming carbamino-Hb

Question 25

Fibrous proteins

Answer 25

Structure: insoluble, polypeptide chain is parallel to single axis, strong and highly cross-linked. Function: structure

Question 26

Collagen

Answer 26

Structure: requires 8 post-translational modifications (enzymes for this are the targets for drugs to inhibit collagen accumulation), primary sequence (1/3 gly)--> minor helix (type II, 3 residue turns)--> triple helix (3 type II stablized by H bonding)-->tropocollagen (post translational modification)-->fibril--> fiber. Function: bone formation.

Question 27

Hydroxylapatite

Answer 27

40nm gaps in collagen fibril serve as nucelation points for hydroxylapatite deposition and bone formation

Question 28

Pre-procollagen

Answer 28

Pre: signal sequence to insert into ER membrane

Question 29

Pro-collagen

Answer 29

Pro: N and C terminal sequences that are cleaved after secretion forming tropocollagen

Question 30

Elastin

Answer 30

Protein of tendons and blood vessel walls. Gives structure ability to spring back into shape. Contain cross links called desmosine (4 lys residues) that provide elastic property. Random coil conformations

Question 31

Fibrillin

Answer 31

Glycoprotein essential for elastic fiber assembly by forming microfibrillar arrays. Scaffold for elastin deposition. Mutation leads to Marfan's syndrome

Question 32

Mad cow disease

Answer 32

Prion disease (infectious proteins), form amyloids which disrupt normal tissue structure. alpha helix --> beta-sheet (insoluble)

Question 33

Cretzfeldt-Jacob disease

Answer 33

Prion disease (infectious proteins), form amyloids which disrupt normal tissue structure. alpha helix --> beta-sheet (insoluble)

Question 34

Spongiform encephalopathies

Answer 34

Prion disease (infectious proteins), form amyloids which disrupt normal tissue structure. alpha helix --> beta-sheet (insoluble)

Question 35

Sickle cell disease

Answer 35

Glu--> Val (generates hydrophobic patch on surface of deoxyHb), causes aggregation via hydrophobic interactions with pocket. Aggregate distorts the shape of the RBC into a sickle shape

Question 36

Ehlers-Danlos

Answer 36

Connective tissue disorder. Collagen defect due to AA substitution that disrupts triple helix formation or enables intermolecular disulfide bonds which form molecular aggregates. Sym: skin hyperflexability, joint hypermobility, tissue fragility, patchy hair

Question 37

Osteogenesis imperfecta

Answer 37

Mutation in structural collagen gene. Brittle bone disease, all bones broken at birth

Question 38

Marfan's Syndrome

Answer 38

Connective tissue disorder caused by mutation in fibrillin-1 gene. Sym: weak tendons, ligamnets, connective tissue, blood vessels. Direct tropoelastin deposition during fibrilogenesis