BIOCHEM 2 - PROTEIN FUNCTION Flashcards Preview

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Flashcards in BIOCHEM 2 - PROTEIN FUNCTION Deck (76):
1

Most abundant protein in animals




collagen

2

SOLUBILITY OF COLLAGEN IN WATER

Water-insoluble fibers

3

Location of collagen in the cell

extracellular

4

Has great tensile strength (due to aldol crosslinks)

collagen

5

contributes to great tensile strength of collagen

aldol crosslinks

6

major role of collagen

stress-bearing component of connective tissues

7

location of collagen in body

Cartilage, bones, tendons, ligaments & skin

8

Primary Structure of collagen

-(-X–Y–G-)-
- X–Pro/Hyp; Y–any aa
- each chain is about 800 aa residues long

9

Secondary Structure of collagen

- Left-handed α-helix
- 3.3 aa/turn
- Pitch: 10 Å

10

Tertiary structure

- 3 chains are parallel & wind each other in a right-handed manner to form a triple-helical structure
- H-bond involving Hyp and Hyl residues
- intramolecular and intermolecular aldol covalent crosslinks

11

Structural proteins
Found predominantly in walls of arteries, lungs, intestines and skins

elastin

12

“slide & stretch” over one another to maintain structural integrity and provide recoil

Elastin

13

MW of elastin

MW = 72 kDa;

14

hydrophobicity of elastin

highly hydrophobic

15

Connective tissue protein; has elastic properties



elastin

16

Consists predominantly of nonpolar aa residues, 1/3 G, 1/3 V + A, rich in P

elastin

17

protein having Random coil conformation

elastin

18

protein having Intramolecular and intermolecular desmosine crosslinks

elastin

19

is formed from three allysyl side chains plus one unaltered lysl side chain from the same or neighbouring polypeptide.

A desmosine cross-link

20

responsible for the rubber properties of elastin

A desmosine cross-link

21

Hemeproteins; conjugated proteins

myoglobin
hemoglobin

22

Responsible to the red color of the blood
Prosthetic group (non-protein part)
Porphyrin ring
Centrally bound Fe+2

heme

23

Monomer
Contains a heme




myoglobin

24

primary structure of myoglobin

1 Structure: 153 aa

25

secondary structure of myoglobin

2 Structure: Helical

26

tertiary structure of myoglobin

3 Structure: Globular

27

Found in skeletal and cardiac muscle

myoglobin

28

Folded globin chain forms a crevice which encloses a heme group

myoglobin

29

Heme group of myoglobin is inside the protein since it’s

hydrophobic

30

Roughly spherical molecule found in red blood cells


hemoglobin

31

Transport O2 from lungs to every tissue in the body

hemoglobin

32

Each globin chain of hemoglobin binds a heme group through the______ of a ____________

imidazole ring of a distal histidine residue

33

Globin of hemoglobin binds the heme at the (site)

5th site – “distal histidine site”

34

Tetramer: α2β2
Each subunit contains one heme

hemoglobin

35

each subunit of hemoglobin contains how many heme

1
total of 4 heme

36

how many heme does hemoglobin have

4

37

primary structure of hgb

α = 141 aa
β = 146 aa

38

secondary structure of hgb

helical

39

tertiary structure of hgb

globular

40

quaternary structure of hgb

4 folded chain in tetrahedral arrangement

41

O2 and CO2 have different binding sites

Oxyhemoglobin
Carbaminohemoglobin
Carboxyhemoglobin
Methemoglobin

42

Decrease in pH causes
(2)

release of O2 and converts oxyhemoglobin to deoxyhemoglobin.

43

Genetically altered hemoglobin

sickle cell anemia

44

in sickle cell anemia which aa is defective

6th aa of β subunit
Glu Val

45

Regulatory proteins
Endocrine hormones


INSULIN & GLUCAGON

46

responsible for carbohydrate homeostasis


INSULIN & GLUCAGON

47

Produced from β-cells of Islets of Langerhans


INSULIN

48

regulatory protein with 2 polypeptide chain
(51 aa residues)


INSULIN

49

protein having
Intermolecular and intramolecular disulfide linkage


INSULIN

50

Hypoglycemic hormone


INSULIN

51

linkages found in insulin

Intermolecular and intramolecular disulfide linkage

52

Produced from α-cells of Islets of Langerhans

glucagon

53

Single polypeptide chain
(29 aa residues)

glucagon

54

Involved in increasing the blood levels of glucose

glucagon

55

how many aa residues are in a single polypeptide chain of glucagon

29 AA residues

56

how many aa residues are in insulin

51 AA residues

57

DISEASES RELATED TO INSULIN

Hypoglycemia
Hyperglycemia
Diabetes mellitus

58

Defense proteins
Also known as antibodies

immunoglobulins

59

secrete antibodies

B lymphocyte:

60

is a protein that is produced by the body in response to an “invading” (foreign) substance.

An antibody

61

- are produced as part of the body’s immune response to protect itself.

An antibody

62

is the substance that the body is trying to “fight off” (eliminate or reduce) by mounting an immune
response

antigen

63

Y-shaped molecule
Tetramer


immunoglobulins

64

linkages found in immunoglobulins

Interchain and Intrachain disulfide linkages

65

chains of immunoglobulins

Light Chain
Heavy Chain

66

regions of immunoglobulins

Constant Region
Variable Region

67

Antibody that is commonly found in human secretions like tears, mucous and saliva

IgA

68

Cell attached antibody which function is still under study

IgD

69

Antibody responsible for allergic reactions

IgE

70

Most dominant antibody in humans. This antibody is responsible for secondary immune response

IgG

71

The antibody which serves as protection for primary infections

IgM

72

DISEASES related to immunoglobulins

Autoimmune Diseases
Inherited Immunodeficiency
HIV

73

In what oxidation state must the iron atom be for the heme to bind oxygen

Fe (II), +2

74

Which type of hemoglobin binds more tightly to oxygen, fetal or adult?

Fetal

75

is hemoglobin an allosteric enzyme

yes

76

the affinity of fetal hemoglobin for oxygen is higher than

that of maternal hemoglobin

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