Collagen Flashcards

1
Q

What is the shape of fibrous proteins?

A

Long, rod like cylindrical shaped

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2
Q

Do fibrous proteins have a high or low solubility in water?

A

Low

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3
Q

What are examples of fibrous proteins?

A

Collagen, keratin, tropomyosin

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4
Q

Keratin relates to what?

A

Hair/nails

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5
Q

Tropomyosin refers to what?

A

Muscle

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6
Q

What is collagen?

A

Major insoluble fibrous proteins found inside extracellular matrix and connective tissue

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6
Q

Collagen is found in all _____ and _____ to provide framework to give tissues its form and strength.

A

Tissues and organs

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7
Q

About how much protein in your body is made up of collagen?

A

1/4 or 25%

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8
Q

How much does your skin produces collagen?

A

About 74%

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9
Q

The structure of alpha-helix is cross-linked by what?

A

Disulfide bonds

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10
Q

What are examples of alpha-helix structures?

A

Alpha keratin of hair, feathers and nails

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11
Q

What are examples of BETA conformation structures?

A

Silk fibroin

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12
Q

What are examples of collagen triple helix structures?

A

Collagen of tendon, bone matrix

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13
Q

What kind of turn is an alpha chain collagen?

A

Left hand turn

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14
Q

What kind of turn is an alpha helix?

A

Right hand turn

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15
Q

What kind of turn is a triple helix?

A

Right hand turn

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16
Q

A triple helix has 3 ____?

A

Identical chains

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17
Q

Glycine is ALWAYS positioned at what position?

A

3rd

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18
Q

How many residues/turns does collagen have?

A

3

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19
Q

How many residues/turns does alpha helix have?

A

3-6

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20
Q

In a cross section of collagen model, how is each strand bonded to other strands?

A

Hydrogen bonded

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21
Q

In a cross section of a collagen model, Glycine must appear at what space?

A

Every 3rd space

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22
Q

Where are pyrrolidone rings located in during cross section of a collagen model?

A

On the outside

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23
Q

What are the steps of Hydroxylation of Pro Residues in Pro Collagen?

A

Pro residue + Ketoglutarate + O2 –> 4-hydroxyprolylresidue + Succinate + CO2

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24
Q

What is the enzyme required for hydroxylation of pro residues in pro collagen?

A

Prolyl Hydroxylase and ascorbate (vitamin C)

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25
Q

What is collagen glycosylation?

A

Addition of sugar to hydroxylysine

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26
Q

What does the addition if sugar to hydroxylysine do?

A

Stabilizes the triple helix of collagen

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27
Q

What are the steps of the Biosynthesis of Type 1 Collagen?

A
  1. Synthesis of pro-alpha collagen
  2. Hydroxylation of selected prolines + lysines
  3. Glycosylation of selected hydroxylysines
  4. Self assembly of 3 pro alpha chains
  5. Pro collagen triple helix formation
  6. Secretion
  7. Cleavage
  8. Self assembly into fibril
  9. Aggregation of collagen fibrils to form collagen fiber
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28
Q

A covalent cross-linked collagen does what?

A

Strengthens fiber

29
Q

In covalent cross-linked collagen, Lysol oxidase reaction creates ____ to react with a _____ to form a _____.

A

Aldehyde; lysine; schiff base

30
Q

What does oxidized lysines react with to form crosslinks?

A

Themselves or hydroxylysine

31
Q

Type I, II, and III are what type of collagen?

A

Fibrillar (most abundant type)

32
Q

What are Type I collagen representative tissues?

A
  1. skin
  2. tendon
  3. bone
  4. ligaments
  5. dentin
  6. interstitial tissues
33
Q

What are Type II and Type IX representative tissues?

A
  1. Cartilage

2. Viterous humor

34
Q

What are type III representative tissues?

A
  1. SKIN
  2. MUSCLE
  3. BLOOD VESSELS
35
Q

What type of collagen is Type IX?

A

Fibril associated

36
Q

What type of collagen is type IV?

A

Sheet forming

37
Q

Type IX has what kind of domain?

A

Fibrous and globular

38
Q

What are type IV representative tissues?

A

All basal laminaes

39
Q

What is OSTEOGENESIS IMPERFECTA?

A

Disease associated with collagen metabolism:

  1. Mutation in type 1 collagen and alpha chain
  2. Characterized by brittle bones
  3. Autosomal dominant (severe)
40
Q

What is Ehlers-Danlos Syndrome?

A

Disease associated with collagen metabolism:

  1. Joint hypermobility
  2. Easily bruised
  3. Stretchable skin -> elasticity of skin
41
Q

What is Scurvy?

A

Disease associated with collagen metabolism d/t the lack of hydroxylation of lysine and proline in collagen:

  1. “Liver” spots on skin
  2. Spongy gums, -> tooth loss
  3. Fingernails decay
42
Q

Lysine and proline in collagen is the _____ for hydroxylation of proline (vitamin C)

A

Ascorbate

43
Q

What are the 2 types of collagenases?

A
  1. Tissue

2. Bacterial (Clostridium Histolyticum)

44
Q

Tissue collagenase:

A

Metalloenzymes involved in tissue remodeling or tumor invasion

45
Q

Clostridium histolyticum:

A

Activity of toxin O involved in development of gas gangre

46
Q

Collagenases also play a role in what?

A
  1. COPD (Chronic Obstructive Pulmonary Disease)

2. Cancer metastasis

47
Q

Do fibrous proteins or globular proteins contain larger amounts of secondary structure?

A

Fibrous proteins

48
Q

What type of fibrous protein structure is characterized by tough, insoluble protective structures of varying hardness and flexibility?

A

Alpha helix

49
Q

What type of fibrous protein is characterized by soft, flexible filaments?

A

Beta conformation

50
Q

What type of fibrous protein structure is characterized by high tensile strength, without stretch?

A

Collagen triple helix

51
Q

Does the single strand polypeptide sequence of collagen adopt a left hand or right hand helical structure?

A

Left hand

52
Q

In the collagen triple helix, what amino acid increases the stability b/c the side chains repel each other and extend/stretch the chain?

A

Proline

53
Q

What amino acids that are found in collagen are absent in globular proteins?

A

Hydroxyproline and hydroxylysine

54
Q

What characteristic of collagen structure produces the cross-striations?

A

A staggered alignment and cross-linking

55
Q

What are the 3 hydroxylated amino acids in collagen?

A

4-hydroxyproline, 3-hydroxyproline, and 5-hydroxylysine

56
Q

The hydroxylation of proline can’t occur in what conditions?

A

Anaerobic

57
Q

Proline reacts with what other two substrates in the hydroxylation reaction?

A

Alpha ketoglutarate and Oxygen

58
Q

What are the biproducts made in the hydroxylation of proline?

A

Succinate and CO2

59
Q

What is the only amino acid that can be glycosylated in collagen?

A

Hydroxylysine

60
Q

Glycosylation of hydroxylysine involves the addition of what two sugars?

A

Glucose and galactose

61
Q

What organelle does the assembly of collagen fibers begin in?

A

ER

62
Q

What sets of the biosynthesis of type I collagen occurs before the collagen can be secreted from the ER?

A

Procollagen triple helix formation

63
Q

What amino acid is found at the C-term in collagen to initiate wrapping?

A

Cysteine

64
Q

What enzyme is used to make the aldehydes that react with lysine to forma a Schiff base for cross-linking in collagen?

A

Lysol amino oxidase

65
Q

Are lysine cross links more prominent in triple helical or non-triple helical regions?

A

Non-triple helical

66
Q

Type IV collagen and laminin form what which are held together by other proteins?

A

Scaffolds

67
Q

What is the basic unit involved in Type IV collagen?

A

Tetramer

68
Q

The severe form of osteogenesis imperfect has what type of inheritance?

A

Autosomal dominant

69
Q

What are the 3 important amino acids in collagen?

A

Proline, hydroxyproline, glycine

70
Q

Which of the following is critical for proline hydroxylation?

A
ATP
Ascorbate ***
Mg2+
Gluthathione
CO2
71
Q

Scurvy results from the dietary deficiency of what?

A

Ascorbic acid