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Bcem 431 > Lecutre 13 > Flashcards

Lecutre 13 Flashcards

1
Q

What is an example of a protein that has a gpi anchor

What disease does it contribute to

A

The prion protein on its c terminal domain

Mad cow disease

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2
Q

What causes mad cow disease

A

Being prion protien being resistant to Proteinase K

Can’t be chopped up and causes other protiens to misfold

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3
Q

What is does a normal prion protein look like (prpc)

A

Has a hydrophobic region

Binds cu2+ in square pyramidal geometry (binds nitrogen’s so intermediate)

Has glycosylated recptors

Has an octa repeat peptide

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4
Q

What is the sequence of the octa repeat residues in the prion protien

A

PH GGG WGQ

these repeats bind the copper ions

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5
Q

What is the disease version of the prion protein

A

Prpsc

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6
Q

What are the types of prion diseases

A

Creutzfeild Jakob disease : due to old age or exposure to infected cow/human brain)

BSE: when cows are exposed to infected cow brain (mad cow diease)

Kuru: humans ingest infected human brain

Fatal familial insomnia : rare Mutation in PRNP (prion protien) gene

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7
Q

What are prion protiens important for

A

Neuroprotection

Signalling in the brain due to gpi anchor

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8
Q

What is the role of the phospholipase enzyme (PI-PLC)

A

It can cleave the gpi anchor chain from the membrane

So I release the proton and the anchor in the extracellular space

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9
Q

Cysteine Thiol groups are

A

Redox sensitive (oxidative vs reducing environment)

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10
Q

What is HSA

A

Human serum albumin

Most important protein in the blood serum

Has 7-9 fatty acid binding sites

Heart shaped

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11
Q

Where is HSA mainly made, as what type of protein

A

In the liver

As a preproprotein

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12
Q

Molecular weight of HSA

A

66kDa

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13
Q

The half-life of HSA is

A

Long

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14
Q

HSA in the plasma is

A

Very densely packed

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15
Q

Is HSA a glycoprotien

A

No

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16
Q

How much of protein in the blood serum is HSA

A

60%

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17
Q

Is there more HSA outside the blood vessels or inside

A

More HSA outside the blood vessel

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18
Q

What is the function of HSA in the blood vessels

A

To maintain the osmotic pressure of plasma inside the cells

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19
Q

What can you say if HSA is not found in the urine

A

This means that HSA doesn’t usually leave the blood

We don’t lose HSA, very kept inside the blood

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20
Q

What does HSA bind

A

fatty acids 7-9 in the plasma

steroid and thyroid hormones (like thyroxine)

Hemin

Metal ions like cu ni zn 2+ (intermediate metals)

21
Q

What is hemin

A

Same as hemoglobin but instead of oxygen bound to fe , cl is bound

The chlorine turns fe2+ to 3+ (ferric)

22
Q

Structure of thyroxine

A

Slide 9

23
Q

How many binding sites does HSA have

A

Multiple

Ex. Binds 1 hemin and 7 fatty acids at the same time

24
Q

HSA is mainly ______

How many domains is HSA

how many subdomains

What is it cross linked by

How many drug binding sites

A

Alpha helical

3

2 in each of the 3 domains

Disulphide bonds

2

25
Q

Why does HSA have disulphide bonds

A

Because it is outside the cell in oxidize environment

26
Q

How many free cysteine in HSA

A

1 rest are disulphide bonds

27
Q

Where do the disulphide linkages occur in HSA

A

Only in between the subdomain in each of the three domain

None in between the three domains

28
Q

Where can we make recombinant HSA and why

A

Only in yeast strains since ecoli can’t make disulphide bonds

29
Q

Where can we make recombinant HSA and why

A

Only in yeast strains since ecoli can’t make disulphide bonds

30
Q

What is the ATCUN site

A

This is the site in the HSA that binds copper and nickel at the amino terminal

Binds cu2+ and ni2+ (square planar, intermediate)

31
Q

What is the most importantly amino acid in the HSA ATCUN site

A

The histidine

Since it’s imidazole ring binds the intermediate metals via nitrogen

32
Q

What where does HSA deliver cu2+

A

Important do cu2+ going To the liver

33
Q

What is the largest pool of copper?

Second largest

A

Ceruloplasmin

HSA

34
Q

HSA also has a _____ binding site

A

Zinc2+

But doesn’t binds to the ATCUN site

35
Q

What amino acids and in which domains make the zinc binding site in HSA

A

Between domains 1 and 2

two his side chains

36
Q

What releases the zinc from the zinc binding site

A

If a fatty acid binds to HSA

Then the two his that bind the zinc are too far apart and the zinc is released

So zinc being there depends on fatty acid binding

37
Q

How many fatty acids can bind to HSA

What types does it bind to

A

7-9 sites for each fatty acid

They are buried in the HSA because they’re hydrophobic

Binds both saturated and unsaturated fatty acid

38
Q

What drug binds to site 1 of HSA

Site 2

A

Warfarin (blood thinner, prevent blood clot forming, block rectivation of vitamin K)

Diazepam (also called Valium, anti anxiety drug)

39
Q

Ka=1/kd

A

Okay slide 17

40
Q

Why does HSA bind many drugs and synthetic drugs

A

It’s like a drug and fatty acid buffer

If you have a drug that has a high response rate to the dose

HSA binding allows for the drug to diffuse and transport through the blood so we don’t get high dose response rate and high dose in one area

41
Q

What is propofol

A

It’s a drug that is very dangerous because it has a high dose response rate and doesn’t bind to HSA

Killed Micheal Jackson

42
Q

Where is the third drug binding site in HSA

What binds there

A

The 1B domain

Billiverdin and hemin bind here

43
Q

Is there competition for drugs at the different binding sites of HSA

What types of interactions do these binding sites have

A

Yes

Allosteric interaction (binds one then the other with higher affinity)

44
Q

Where is drug binding site 1 located

What about 2

A

Domain 2a

Domain 3a

45
Q

If a drug is hydrophobic it’ll bind to

A

Fatty acid binding sites

46
Q

What is methotraxate

How can it get displaced and what’s the result

A

Used as a drug in treating cancer in high doses and rheumatoid artheritis in low doses

NSAIDS (naproxen) displace methotrexate and increase free methotrexate levels in the plasma (toxic competition)

47
Q

How can cancer tumours benefit with HSA

How do we stop this

A

They bind HSA and use it as a source of nitrogen

We can bind anti cancer drugs to HSA so the the tumour attached to HSA dies

Not specific tho, just randomly binding hsa

48
Q

What another example of coupling drug to HSA

A

The one free cysteine (cys34) get drugs attached to it

Bcem 431 (26 decks)

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