Malac Medical Study > BC141: plasma proteins > Flashcards

BC141: plasma proteins Flashcards

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1
Q

What is the biomedical importance of albumins in plasma?

A

they facilitate the transport of fatty acids and ligands like steroid hormones.

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2
Q

What does transferrin do?

A

aid in the uptake and distribution of iron

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3
Q

What plasma proteins work together during clot formation?

A
  • fibrinogen as a readily mobilized building block of fibrin mesh in clots. Used to seal injured vessels.
  • antithrombin, which confine clot formation to the vicinities of the wound.
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4
Q

What are some proteins that act as inhibitors of proteolytic enzymes?

A
  1. antithrombin
  2. alpha-antiproteinase
  3. alpha2- macroglobulin
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5
Q

What is the function of antithrombin

A

confine formation of clot

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6
Q

functionof alpha-antiprotease and alpha2-macroglobulin

A

shield healthy tissue from the proteases that destroy invading pathogens and remove dead/defective cells

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7
Q

What form the front line of the body’s immune system?

A

immunoglobulins: antibodies

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8
Q

What are the pathologies that reflect the biomedical importance of plasma proteins?

A

1.Hemophilia
2. Wilson’s disease
3. emphysema
2. HIV and immunosuppressant drugs

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9
Q

How can hemophilia occur?

A

deficiency in key components of:
blood clotting cascade

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10
Q

How does hemophilia manifest?

A

excessive bleeding and bruising

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11
Q

Etiology of Wilson’s disease

A

lack of blood ceruloplasm, the primary transporter of copper in the body

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12
Q

What does Wilson’s disease cause?

A

hepatolenticular degeneration

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13
Q

What is emphysema often associated with?

A

a genetic deficiency in the production of circulating alpha-antiproteinase

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14
Q

In what conditions may an insuffieciency in the production of protective antibodies occur?

A
  1. HIV-infected persons (human immunodeficiency virus)
  2. patients that are administered immunosuppressants
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15
Q

What may this insuffiency in antibodies cause?

A

extreme susceptibility to infection by microbial and viral pathogens

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16
Q

What is plasma composed of?

A
  1. water
  2. nutrients
  3. metabolites
  4. hormones
  5. electrolytes
  6. proteins
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17
Q

What does plasma maintain?

A

body fluid between tissue and blood

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18
Q

What is the mechanism in which plasma maintains body fluid?

A
  1. arterial blood enters capillaries
  2. fluid moves from intravasc. to interstitial space (water leaving the capillaries to enter extravascular spaces)
  3. at venous end, fluid moves back from interstitial spaces to the blood.
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19
Q

What force causes movement of fluid at the capillary- interstitial connection?

A

Startling’s force, which regulates the movement of fluid at this region. It is caused by two pressures:
1. hydrostatic pressure
2. osmotic pressure of the plasma proteins

the difference between the hydrostatic pressure in arteriolar end (37mmHg) and sum of tissue pressure (1 mmHg). Pressure difference causes water to enter extravascular spaces

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20
Q

What changes occur to pressure?

A
  1. hydrostatic pressure: changes from arteriolar to venous end of capillary. falls to around 17mmHg
  2. osmotic pressure: unchanged (constant)
  3. tissue pressure: unchanged
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21
Q

What force causes the water to go back into the blood?

A

The osmotic pressure, mediated by proteins in plasma

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22
Q

How does the presence of proteins in plasma contribute to the movement of body fluid?

A

They are responsible for the reuptake of water in venous-end capillaries.

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23
Q

How are plasma protein groups divided from each other in a blood test?

in lab

A

via cellulose acetate zone electrophoresis

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24
Q

What are the three groups of plasma proteins?

A
  1. albumins
  2. fibrinogen
  3. globulins
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25
What are the steps to cellulose acetate zone electrophoresis?
1. small amount of serum applied to cellulose acetate strip 2. electrophoresis in electrolyte buffer is performed 3. staining separates bands of protein visually 4. densitometre scans reveals relative mobilities of plasma proteins
26
What are the plasma proteins that are revealed by the densitometre?
- albumins - a1- globulin - B2- globulin - B-globulin - Y- globulin (gamma)
27
What are plasma proteins rich in?
- disulfide bonds - often contain bound carbohydrates or lipids: glycoproteins and lipoproteins
28
Where are plasma proteins synthesized?
1. liver 2. vascular endothelium 3. lymphocytes
29
What are the plasma proteins that are synthesized in the liver?
1. albumin 2. fibrinogen 3. transferrin 4. complements: blood clotting cascade
30
Synthesized in vascular endothelium...
the von Willebrand factor
31
In general, where are plasma proteins made?
In the liver, where 70- 80% of all plasma proteins are synthesized.
32
What is the exception/ not synthesized in the liver?
gamma-globulins: strictly lymphocytes that originate from **bone marrow** (along with in other lymphoid organs)
33
What do lymphocytes synthesize gamma-globulins?
gamma-globulins
34
What changes in plasma proteins may occur in lymphocytes?
1. modification of **most** plasma proteins 2. polymorphisms
35
How are plasma proteins modified?
**covalent modification** addition of: 1. N-linked oligosaccharide chains 2. O-linked oligosaccharide chains 3. both N- and O-linked oligosaccharide chains
36
What is polymorphism?
A difference in the amino acid sequence that does not affect the formation of a given protein.
37
What causes polymorphism?
when a plasma protein contains a - mendelian - monogenetic trait that exists in the population in at least **2 phenotypes** with both being fairly common
38
What is the minimum frequency of a given polymorphism in the population?
When its frequency is at least 1-2%
39
T/F: polymorphism is harmful and can cause diseases
False. Most are **innocuous** (not harmful), however they can determine which diseases an individual may be more susceptible to.
40
Which plasma proteins have poolymorphism?
1. ABO group 2. a1-antitrypsin 3. haptoglobin 4. tranferrin 5. ceruloplasmin 6. immunoglobulins
41
Define half-life of plasma proteins
TIme required for 50% of the molecules present at a given moment to be degraded/eliminated from the blood - outcome: time required
42
1/2 life of albumin | in adults
20 days
43
5 day 1/2 life | of a given protein in adults
haptoglobin
44
# in normal circumstances... What is the process that replaces old proteins with newly synthesized ones?
turnover
45
What might **markedly** alter 1/2 of protein?
certain diseases
46
Which GI disease may affect the 1/2 life of plasma proteins?
Crohn's disease
47
What does Crohn's disease do? | why?
a considerable amount of proteins are lost in the bowel due to: - **inflamed intestinal mucosa**
48
What is the main protein that is affected by Crohn's disease?
albumin - 1/2 of albumin (which is normally 20 days) can be reduced to as little as 1 day
49
What is Crohn's disease referred to as?
protein-losing gastroenteropathy
50
What is the most common plasma protein?
albumin - quantity: 60% of plasma proteins - osmotic pressure: 70- 80% of total plasma osmotic pressure
51
Why is it the most common?
small in size and M.W: 69kDa - three fifths of total p.p weight (g/dL)
52
What is albumin and what does it carry?
It is a glycoprotein (like most plasma proteins). Carries: 1. free F.A. 2. calcium 3. zinc 4. steroid hormones 5. copper 6. bilirubin
53
How much albumin is synthesized by the liver? What proportion of liver protein synthesis is of albumin?
12 g per day - 1/4 of total hepatic protein synthesis, **1/2** of its secreted proteins
54
How much of the total body albumin circulates in the plasma?
40% of albumin
55
Where does the remaining 60% of albumin reside?
In extracellular space
56
How are most proteins secreted? | In what form
Preprotein
57
Characteristics of mature human albumin:
- single polypeptide chain - 585 amino acids - 3 functional domains - 17 intrachain disulfide bonds
58
What drugs may bind to albumin?
- sulfonamides - penicillin G - dicumarol - aspirin (important pharmacological implications)
59
What can albumin be used to treat?
1. burns 2. hemorrhagic shock
60
What are some types of proteins found in plasma?
1. albumins 2. acute-phase proteins 3. ferritin 4. transferrin
61
What are acute-phase proteins?
Proteins that respond to inflammation
62
What are examples of alpha-phase proteins?
1. C-reactive proteins (CRPs) 2. fibrinogen 3. haptoglobin 4. a1-antiproteinase 5. a1- acid glycoprotein
63
What is analbuminemia?
a rare genetic defect that causes little production of serum albumin. - mutations in gene causes impairment of the ability to synthesize albumin
64
What are symptoms shown in analbuminemia?
1. moderate edema (not severe) 2. low albumin to globulin ratio (decrease in ratio)
65
What is a unique characterisitic of analbuminemia in conditions of protein malnutrition?
(ex. **Kwashiorkor**) - the decrease in albumin synthesis is pretty **early on**
66
Why is CRP named that?
C-reactive protein - because it reacts with the **C polysaccharide of pneumococci**
67
What does CRP do?
it stimulates the classical complement pathway, an immunological pathway that creates an activation cascade of protein to create a membrane-attack complex that pokes holes in pathogens. (MAC)
68
When do you see an increase in acute-phase protein levels? Which one increases the most?
- during chronic inflammatory states - in cancer patients increase from 0.5 to 1000 fold. - CRP increases by 1000 fold
69
Considering the degree of increase in acute-phase plasma protein, which acts a biomarker and a bbiomarker of what exactly?
CRP CRP is a biomarker of: 1. tissue injury 2. infection 3. inflammation
70
T/F fibrinogen is a type of albumin.
False. It is an acute-phase protein
71
Where is fibrinogen located?
- circulating in blood - in platelet granules
72
What are the characterisitcs of fibrinogen?
- 2 triple helices - helices held together with **disulfide bonds**
73
What does fibrinogen bind to?
activated platelets
74
What is the binding of fibrinogen necessary for?
Aggregation, as it is part of the mechanism of platete adhesion.
74
What cleaves fibrinogen
thrombin: a serine protease that is a **potent activator of platelets**
75
What activates thrombin?
the coagulation cascade
76
What does cleavge of fibrinogen produce?
fibrin monomers. - these monomers polymerize and create a **soft clot** with the platelets.
77
How does thrombin activate platelets?
via binding to a specific receptor on the platelet surface
78
Fibrinogen cleavage results in...
clot formation
79
Where and how is fibrinogen joined together?
- at N-terminal ends disulfide bonds between (to themselves): 1. alpha-/ beta-peptides 2. gamma peptides - terminal a/b peptide regions: negatively-charged glutamate and aspartate residues
80
What prevents the aggregation of the terminal ends of fibrinogen?
the glutamate and aspartate residues that repel each other.
81
How does thrombin cleave fibrinogen?
by cleaving the terminal portions that contain (-) charges. (at glutamate and aspartate residues)
82
What is the soft clot from fibrin monomers cross-linked by?
another enzymes (other than thrombin)
83
What is haptoglobin?
a plasma glycoprotein that binds **extracorpuscular** hemoglobin (Hb).
84
What are the characteristics of haptoglobin?
depends, there are 3 polymorphic forms: 1. Hp 1-1 2. Hp 2-1 3. Hp 2-2
85
What do the polymorphic forms reflect?
patterns of inheritance of **2 genes**: - Hp1 - Hp2
86
What do different genotypes manifest as phenotypically?
1. homozygotes: Hp1-1 and Hp 1-2 2. heterzygotes: Hp 2-1
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