Protein Structure 2 Flashcards

1
Q

What determines the charge on the protein?

A

The pH and the number and type of each amino acid residues with ionisable sidechains

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2
Q

What is the pH inside lysosomes and why?

A

pH is 4.5/5

to activate the enzymes

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3
Q

Van der Waal interactions
What range is its effect?
Is it weak or strong?
How is it broken?

A

Very short range effect
Weak electrostatic forces
Broken by heat and denaturing agents

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4
Q

What energy is the best for protein folding?

A

Lowest energy minimum

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5
Q

What are protein domains?

A

Areas of protein that fold independently

these often perform a specific function

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6
Q

Is amorphous aggregation is non specific ?

A

It is non specific

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7
Q

Why is Amyloid proteins cause illness?

A

They can form multiple disordered proteins spontaneously

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8
Q

What 5 things can disrupt protein structure

A
Ionic Strength
pH
heat ( 20-40C)
denaturing agent 
UV / oxidative / radiation damage
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9
Q

Can proteins be modified after they are made?

A

yes

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10
Q

Interactions can be what?

A

Interactions can be transient or stable

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11
Q

Name an example of how a protein can be modified

A

Can have prosthetic groups

proteins compete for binding sites

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12
Q

What percentage of proteins have a form that differs from their genetic sequence?

A

44%

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13
Q

What is a proteoform?

A

proteoform is used to denote all the molecular forms in which the protein product of a single gene can be found

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14
Q

When do reactions of sidechains that drive the addition of chemical groups?

A

It occurs post translation

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15
Q

Name 7 modifications that can occur to a protein

A
Phosphates
Lipids
Acetylation
Methylation
Proteins
Glycans/carbs
Proteolytic maturation
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16
Q

Which three amino acids commonly phosphate

17
Q

What is phosphorylation important in?

A

Important in downstream cellular signal

18
Q

What enzyme phosphorylates?

19
Q

What enzyme dephosphorylates?

20
Q

Describe glycosylation

A

Addition of complex carbohydrate groups

N-linked to Asn or O-linked to Ser/ Thr

21
Q

What is palmitoylation?

A

Long lipid groups help anchor proteins in membrane

Modification on cysteine, glycine, lysine

22
Q

Which amino acids side chain can be used to make isopeptide bonds?

A

The lysine side chain can be used to make isopeptide bonds with the carboxyl
terminus of ubiquitin

23
Q

What are Zymogens?

A

Precursors of enzymes that are activated in a proteolytic cascade after release as granules into the duodenum

24
Q

Name 3 examples of groups that can be conjugated that are non protein

A

Heam
Lipid
Mental ion
Nucleic Acid

25
What is the meaning of homomeric and hetromeric?
``` Homomeric= all the same units Heteromeric= differing units ```
26
What do oligomeric interactions of the proteins require? | What are these driven by?
Complementary interfaces , often dormains or motifs | Driven by hydrophobic packing or electrostatic/ polar interactions
27
Interactions between protein can be | t_____ or s_____
Transient or Stable
28
What is PKR?
PKR= kinase that is activated when double stranded RNA is present in the cell
29
What is often a sign of a viral infection in the cell?
Double stranded RNA
30
How does PKR help stop a viral infection
Double stranded RNA binds to the PKR which causes a conformational change and dimerisation so the kinase becomes activated Activated PKR then phosphylates the substrate and switches off general translation hence inhibits the viruses replication
31
Which protein acts in blood to decrease the circulation of elastase?
Alpha-1-antirypsin