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Biochemistry - Block 1 > Biochem Lecture 3 > Flashcards

Biochem Lecture 3 Flashcards

1
Q

How much collagen is found in the human body?

A

1/4 of all protein is collagen

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2
Q

How much collagen is found in skin?

A

74%

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3
Q

How much collagen is glycine residue?

A

33%

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4
Q

How long is collagen?

A

1000 AA long
3000 A long / 300 nm
15 A thick

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5
Q

Collagen triple helix

A
  • glycine groups face inward

- LEFT hand alpha helix but RIGHT hand triple helix

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6
Q

True or False

Collagen contains glycine groups that face outward

A

FALSE

  • glycine groups face inward
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7
Q

Fibrous Proteins

A
  • Contain larger amounts of regular secondary structure
  • Long cylindrical
  • Low solubility in water
  • Structural role
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8
Q

True or False

Fibrous Proteins have low solubility in water

A

TRUE

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9
Q

Collagen, keratin, and tropomyosin

A

Examples of Fibrous Protein

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10
Q

Globular Proteins

A
  • Less secondary structures
  • High solubility in water
  • Dynamic role; meaning gives function to enzymes
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11
Q

True or False

Globular Proteins have a dynamic role

A

TRUE

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12
Q

True or False

Globular Proteins have a low solubility in water

A

FALSE

Globular Protein s have a High solubility in water

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13
Q

What is the most plentiful protein in the human body?

A

Collagen

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14
Q

Collagen

A
  • MAJOR insoluble fibrous protein
  • Gives tissues their strength
  • located in all tissues and organs
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15
Q

Where is collagen located?

A

Extracellular matrix and connective tissue

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16
Q

Collagen Type 1

A

Skin, tendon, bone, ligaments, dentin, interstitial tissues

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17
Q

Collagen Type 2 and 9

A

Cartilage and Vitreous humor

Linked together ultimately make the structure of cartilage

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18
Q

Collagen Type 3

A

Skin, muscle, blood vessels

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19
Q

Collagen Type 5

A

Similar to type 1 but including cell cultures and fetal tissue

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20
Q

Collagen Type 4

A
  • Basal lamina
  • 2D
  • Mesh like network to connect things form scaffolds
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21
Q

Alpha Helix of Collagen

A
  • cross linked by disulfide bonds

- L hand turn

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22
Q

Beta Conformation

A

Silk Fibrion

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23
Q

Collagen basic unit of structure is

A

Triple Helix

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24
Q

Triple helix

A
  • High Tensile strength, without stretch
  • Repeating Tripeptide sequence
  • Each strand is H bonded to the other two strands
25
Q

True or False

Proline R groups are on the outside

A

TRUE

26
Q

True or False

Steric Hindrance does not allow for stretching and elongation of strand which leads to tight twisting

A

FALSE

Steric Hindrance allows for stretching and elongation of strand

27
Q

Does Triple helix have a right or left handed turn?

A

Right
(after all three chains have combined)

The collagen triple helix is made of three collagen peptides, each of which forms its own left-handed polyproline helix

When the three chains combine, the triple helix adopts a right-handed orientation

Normally alpha helix is right handed

28
Q

Glycine is always in the ______ position

A

Third

Due to SMALL side chain, can fit in the middle and is required at the tight junction where the three chains are in contact

29
Q

How many residues per turn?

A

3

Remember the difference - Alpha helix has 3.6 per a turn

Ex: Collagen of tendon, bone matrix

30
Q

Gly-X-Y, Gly-X-Pro, or Gly-X-HPro

A

Repeating Tripeptide Sequence

31
Q

Proline

A
  • Steric Hindrance allows for stretching and elongation of strand which leads to tight twisting
  • Proline R groups are on the outside
  • Each strand is H-bonded to the other two strands
32
Q

Hydroxylated Amino Acids in Collagen

A

4-Hydroxyproline

  • Formation is done by a Pro + Alpha Ketoglutarate and O2 with enzyme prolyl hydroxylase and Ascorbate which results in a 4-Hydroxy Prolyl residue and succinate

NEEDS ascorbate in formation of hydroxyproline

Adds stability

33
Q

What enzymes are used in 4-Hydroxyproline formation?

A

Prolyl Hydroxylase
and
Ascorbate

34
Q

Name the Hydroxylated Amino Acids in Collagen

A

4-Hydroxyproline
3-hydroxyproline
5-hydroxylysine

35
Q

5-hydroxylysine

A

Alpha Chains of Collagen and Collagen Fibrils are CROSSLINKED by unusual types of covalent bonds involving lys, hylys, or His.

36
Q

Collagen Glycosylation

A

Addition of Galactose and Glucose to only hydroxylysine

37
Q

What will the addition of Galactose and Glucose do to the collagen triple helix?

A
  • Stabilizes the triple helix of collagen

Once triple helix forms, glycosylation ceases

38
Q

Biosynthesis of Type 1 collagen

A
  • DNA to mRNA to ribosome forms the single alpha helix as soon as it leaves the ribosome.
  • Alpha helix is hydroxylated on the prolines and lysines
  • Glycosylation of the Hydroxylysine
  • Triple helix formation is in the ER and Golgi. Three alpha helices being put together C to N terminus winding together
  • Once Outside the Cell the Pro collagen molecule will get cleaved to make a mature collagen molecules
  • Mature collagen gets assembled into fibrils
  • Fibrils are held together partially by the covalent linking between lysine and hydroxylysine, histidine
  • Fibrils come together to make a fiber.
39
Q

Enzymes in biosynthesis

A

Enzyme prolyl hydroxylase and, O2, Ascorbate (Vitamin C)

40
Q

Glycosylation of the Hydroxylysine

A

Galactose and Glucose

41
Q

Intramolecular and Intermolecular cross linking can be between

A

lysine
histidine
& hydroxylysine

42
Q

Intramolecular

A

within one chain

43
Q

Intermolecular

A
  • Between different chains and important in the formation of a fibril
  • They overlap by ¼ staggered fashion→ makes striations.
44
Q

Covalent Cross Linking of Collagen

A
  • Strengthens fiber

- Hydroxylysine that has been glycosylated can still participate in crosslinking

45
Q

Covalent Cross Linking of Collagen occurs by:

A
  • Lysl oxidase reaction creates an aldehyde which can reacts with a lysine to form a schiff base
  • and ultimately a cross link in collagen or another way is when two aldehydes react together in an aldol condensation and form an aldehyde cross link
46
Q

Associate diseases with collagen synthesis

A

Abnormal collagen genes, abnormal postranslational modification of collagen or deficiency of cofactors needed by enzymes responsible for translational modification of collagen

47
Q

Diseases of Collagen

A

OSteogenesis
Ehlers-Danlos Syndrome
Scurvy

48
Q

Diseases of Collagen

A 
OSteogenesis 
Ehlers-Danlos Syndrome
Scurvy
Tissue collagenases 
Bacterial collagenase 
Fibril
49
Q

Ehlers-Danlos Syndrome

A
  • Joint hypermobility
  • Easily bruised
  • Stretchable skin
50
Q

Scurvy

A
  • Liver spots on skin
  • Spngy gums→ leads to tooth loss
  • Fingernail decay
    Due to lack of HYDROXYLATION of LYS and PRO in collagen
  • Vitamin C deficiency so lack of collagen production
    (Ascorbate = vitamin C)
51
Q

Tissue collagenases

A

Enzymes that break down collagen, sometimes used to heal a wound but most times used by tumors so the tumors can secrete and break down basement membranes so tumors can invade deeper and ultimately into blood vessels.

52
Q

Bacterial collagenase

A

Clostidrium collagenase

  • Toxin O is a type of collagenase secreted by clostridium that is involved in gas greene.
  • COPD is associated with collagenases due to breakdown of alveoli in lung and cancer metastasis.
53
Q

Fibril

A

Triple helices together to form a fiber
- Triple helix held by
H bonding of glycine resides and can have covalent bonding in it.

  • Fibril Held together by covalent bonds
54
Q

What is the most abundantAmino acid that is required every 3rd position in the collagen sequence?

A

Glycine

55
Q

What results from a constant pattern in collagen?

A

Straistions

56
Q

Cross-links involved in the reaction of lysine residues go through reaction and are stabilized with what?

A

lysyl amino oxidase

Remember- Crosslinks are present in collagen

57
Q

Hydroxylation of proline requires what do that it can take place?

A

Prolyl hydroxylase and theascorbate

58
Q

What is used important for the turnover of collagen?

A

collagenases

Biochemistry - Block 1 (6 decks)

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