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Topic 3 (Proteins Health) Flashcards

1
Q

What type of proteins contain keratin/collagen

A

Fibrous proteins

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2
Q

What type of proteins have repeated AA sequences and have a high hydrophobic AA content

A

Fibrous proteins

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3
Q

What type of proteins are soluble

A

Globular

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4
Q

What % of abnormal haemoglobins is caused by a single AA change?

A

95%

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5
Q

Whats the role of myoglobion?

A

Stores O2 in tissue

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6
Q

Where is myoglobin found predominantly

A

skeletal / cardiac muscle

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7
Q

Structure of myoglobin (helices)

A

8 a-helices

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8
Q

What group does myoglobin contain?

What does this comprise of (2)

A

Haem prosthetic group

Fe(2+) + Protoporphyrin IX

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9
Q

What is haem comprise of? What bonds are present?

A

9 ring

Covalent bonds

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10
Q

What does Proximal Histidine bind to?

What number/symbol is it denoted?

A

Binds to Iron

F8

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11
Q

What does Distal Histidine bind to?

What number/symbol is it denoted?

A

Binds to O2

E7

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12
Q

When Oxygen binds to haem, what moves?

A

Iron moves closer to E7

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13
Q

Structure of Haemoglobin (a/b)

How is it all held together by?

How many O2 can it carry

A

2a / 2b

non covalent bonds

4O2

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14
Q

By how much does haemoglobin differ to myoglobin

A

Differs by 83% AA

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15
Q

What type of protein is haemoglobin in regards to the fact it changes shape

A

Allosteric

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16
Q

Which protein has a higher affinity for oxygen

A

Myoglobin

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17
Q

When haemoglobin binds to Oxygen, conformational changes occur which ruptures what?

What does this allow?

A

Salt bridges rupture

Increases affinity for O2

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18
Q

Which state of haemoglobin is tense and has low affinity for oxygen

What type of bonds are present

A

T state

Many salt bridges

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19
Q

The Bohr effect is based off what principle?

A

Decreasing pH = Decreases affinity for O2

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20
Q

When H+ are high, what AA is protonated?

What does this prevent

A

Histidine residues are protonated

Removes affinity for O2

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21
Q

When H+ is high, what type of AA are protonated?

What does this cause?

A

+ charged AA

Forms salt bridges = T state = decreases affinity for O2

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22
Q

BPG stands for what?

Where is it found in high concentrations

A

Biphosphoglycerate

Erythrocytes

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23
Q

How is BPG increased?

A

hypoxia / high altitudes

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24
Q

What does BPG do to haemoglobin?

A

Decreaes affinity for O2

25
How does BPG work?
Binds only in T state to B subunits -charge on BPG reacts with +AA residues
26
Foetal HB structure
a2y2 (HbF)
27
Out of haemoglobin / myoglobin / Foetal Hb, which has the strongest affinity to O2
HbF
28
Give 2 examples of haemoglobinopathies
Sickle cell B thalassaemia
29
What are the two positions that are a critical AA involved with haem functioning correctly (haem contact)
Phe // Leu (hydrophobic) CD1 / F4
30
What type of substitution still allows funcitoning haemoglobin?
Conservative substitution
31
If Alanine is substituted for isoleucine, what occurs in haemoglobin?
Nothing... both are hydrophobic
32
If Leucine is substituted by Lysine, what occurs in haemoglobin?
Major effect on structure / function
33
Which type of collagen are most common?
types 1/2/3
34
Which type of collagen are found in the basal lamina?
Types 4/7
35
which type of collagen are fibril associated collagens?
Types 5,9, 12
36
Polypeptide synthesis of collagen occurs in which cell?
Fibroblasts
37
What sort of structure is formed before being secreted out of cell?
Procollagen triple helical cable
38
Which type of collagen has extension proteins?
Procollagen
39
What is cleaved off in procollagen? Where is this done?
Extension peptides Extracellular spaces of CT
40
What forms microfibrils?
Tropocollagen
41
Which AA is repeated every 3rd residue?
Glycine
42
What modified AA are present in collagen? What process is done to modify these AA?
Hydroxyproline // Hydroxylysine Hydroxylation
43
When does Hydroxylation occur?
Before Polypeptide chain forms a helix
44
Role of Hydroxyproline?
Stabilises triple helix via H bond formation
45
Role of Hydroxylysine?
Attachment sites for sugar residues
46
What handed helix is each individual chain in collagen? What is the overall direction of tropocollagen?
Left handed helix Forms right handed twist
47
Glycine is found where in the helix?
Packed into centre of chain
48
Where do disulphide bonds form in assembly of collagen?
Between C terminal extensions
49
What is role of lysyl oxidase / allysine oxidase in collagen production?
Stabilising fibrils from tropocollagen via covalent cross links
50
Holes between tropocollagen fibres form what?
Nucleation sites for Ca deposition
51
Role of collagenases?
Repair breakdown of collagen
52
What are collagenases?
Metalloproteinases
53
Where are collageneases found in high volume?
Tumour cells for invasion / metastasis
54
What contracture produces excess collagen in hand
Dupuytrens contracture
55
What treatment can be given for Dupuytrens contracture
Injection of collagenases
56
Ehlers Danlos syndrome is caused by what?
Lysyl oxidase deficiency
57
Symptoms of Ehlers Danlos Syndrome (4)
Joint hypermobility extreme fatigue stretchy skin digestive problems
58
Osteogenesis is caused by what?
Spontaneous mutation in type 1 collagen
59
which type of osteogenesis is the worst for prognosis
Type 4

IMS (25 decks)

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