(M) Lec 5: Amino Acids (P2: Proteins) Flashcards
1
Q
Most plasma proteins are synthesized in what organ?
A
Liver
2
Q
The liver is responsible for producing numerous plasma proteins except for what?
A
Immunoglobulins (aka antibodies which are produced by lymphocytes)
3
Q
This panel is used to test the synthetic function of the liver (if it normally produces the proteins needed by the body)
A
Protein Panel
4
Q
The process of degrading proteins to become free amino acids
A
Protein Catabolism
5
Q
Protein Catabolism Pathways
Degrades extracellular and some intracellular proteins
A
Lysosomal pathway
6
Q
Protein Catabolism Pathways
Important in degrading intracellular proteins
A
Cytosolic pathway
7
Q
- Refers to the removal of amino acid nitrogen from the body
- Removal of an α-amino group (N alone is toxic to the body) from an amino acid by transaminases to a ketocarbon which produces ketoacids
A
Transamination
8
Q
These 2 products of transamination:
1. Are converted to urea by the liver (via the urea cycle)
2. Are converted to glucose/fat (via the Krebs cycle)
(2 answers)
A
- Ammonia
- Ketoacids
9
Q
Protein Structures
- Overall shape and confirmation; there is folding and a 3D configuration (determines the function and phsyiochemical properties)
- Alpha-helix and Beta-pleated sheet (adds strength and flexibility)
- The basic amino acid sequence
- The shape/structure from the interaction of one or more protein molecules/sub-units held by noncovalent bonds
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
A
- C
- B
- A
- D
10
Q
Protein Properties
TOF: Proteins are always negatively charged
A
False (can be BOTH)
11
Q
Protein Properties
Refers to the pH at which amino acids and protein have no net charge
A
Isoelectric Point
12
Q
Protein Properties
- If pH > pI, a protein has a net (+ or -) charge
- If pH < pI, a protein has a net (+ or -) charge
A
- pH > pI = negative
- pH < pI = positive
13
Q
Protein Properties
Basic or Acidic Group?
Lysine, Arginine, and Histidine
A
Basic
14
Q
Protein Properties
Basic or Acidic Group?
Glutamate, Aspartate, Cysteine, and Tyrosine
A
Acidic
15
Q
Protein Properties
If there is a charge at the protein surface, the protein is (hydrophilic or hydrophobic)?
A
Hydrophilic
Note: The charge makes it more soluble
16
Q
Protein Properties
A protein’s lowest solubility is at what point?
A
Its isoelectric point (there is no net charge)
17
Q
Protein Classifications (by function)
- These catalyze chemical reactions
- Most are composed of proteins EXCEPT ribozyme (composed of nucleic acids)
A
Enzymes
18
Q
Protein Classifications (by function)
Chemical signals that are important for the endocrine system
A
Hormones
Can be made up of proteins or steroids
19
Q
Protein Classifications (by function)
These are responsible for carrying certain ions/molecules
A
Transport Proteins
20
Q
Protein Classifications (by function)
- Are antibodies important for the defense mechanism and immunity
- Binds to foreign antigens
- Not produced by the liver but rather the plasma cells
A
Immunoglobulins
21
Q
Protein Classifications (by function)
Examples are fibers, collagen, and keratin
A
Structural Proteins
22
Q
Protein Classifications (by function)
An example is ferritin (iron-storage)
A
Storage Proteins
23
Q
Protein Classifications (by function)
A source of this comes from gluconeogenesis
A
Energy Source
24
Q
Protein Classifications (by function)
- Pressure that holds the fluid inside the blood vessels
- Is greatly affected by albumin therefore this functions to distribute water throughout the different compartments of the body
A
Osmotic Force
25
# Protein Classifications (by structure)
Composed purely of proteins and amino acids
- Globular (enzymes, messengers, transporters, hemoglobin, plasma proteins, and peptide hormones)
- Fibrous/Structural (fibrinogen, troponin, and collagen)
Simple
26
# Protein Classifications (by structure)
Attached to **non-protein molecules**
- An apoprotein + prosthetic group
- **Metalloproteins** - ferritin, hemoglobin, and ceruloplasmin (carries copper)
- **Lipoproteins** - HDL, LDL, VLDL, and chylomicrons
- **Glycoproteins** - anti-trypsin and haptoglobin
- **Nucleoproteins** - chromatin
- **Mucoproteins/Proteoglycans** - mucin
Conjugated
27
# Nitrogen Balance
- Protein catabolism **exceeds anabolism**
- Burns, wasting disease, high fever, and starvation
Negative Nitrogen Balance
28
# Nitrogen Balance
- Protein anabolism is **greater than catabolism**
- Growth, pregnancy, and repair processes
Positive Nitrogen Balance
29
# Plasma Proteins
What are the 2 major groups?
Albumin and Globulin
| Majority is albumin (50-60%)
30
# Plasma Proteins
**Plasma Protein Panel Normal Values:**
1. Total Protein
2. Albumin
3. Globulin
4. A/G Ratio
A. 1.1-1.8
B. 6.5-8.3 g/dL
C. A computed value only
D. 3.5-5.5 g/dL
1. B
2. D
3. C
4. A
| Globulin = TP - Albumin
31
# Plasma Proteins
What is the **SI unit conversion factor** for proteins?
g/dL x 10 = g/L
32
# Serum Protein Electrophoresis
- pH = ?
- Charge of proteins = (+ or -)
- Protein separation and migration move from what point of origin to what end point?
(3 answers)
1. pH = 8.6
2. Proteins are (-) charged
3. From cathode (-) to anode (+)
33
# Serum Protein Electrophoresis
Order the proteins from **most to least abundant** and their migratory distance:
1. Y-globulins
2. Albumin
3. B-globulins
4. A1-globulins
5. A2-globulins
Note: Their **concentrations and migratory distances** are ordered the same
1. Albumin
2. A1-globulin
3. A2-globulin
4. B-globulin
5. Y-globulin
| Study the percentages in the recorded lecture
34
# High Resolution Electrophoresis
Separated into as many as how many bands?
12
| Note: Study the additional zones in the lecture
## Footnote
Additional modifications include: Higher voltage, cooling system, and a more concentrated buffer
35
# Serum Proteins
* Aka **transthyretin**; it migrates ahead of albumin
* Transport protein for **thyroxine (T4) and triiodothyronine (T3)**
* Binds with **retinol binding protein** to form a complex that transports retinol
* Half life:** 2 days**
* Rich in **tryptophan**
* A sensitive marker of **poor nutritional status**
Pre-Albumin
36
# Serum Proteins
* **Highest protein concentration** in the plasma (50-65%)
* Synthesized by the **liver at 9-12 g/day**
* Half life: **20 days**
* **Glycated Albumin** - Fructosamine (alternative to HbA1c)
* Functions:
1. Maintains 80% of **colloid osmotic pressure** (a decrease leads to edema)
2. **Negative** acute phase reactant (decreases when there is infection/inflammation)
3. **Buffers pH**
4. **Transportation** (Iron, Fatty Acids, Bilirubin (B1), Electrolytes, Steroids, Drugs, Hormones)
Albumin
37
# Albumin
Increased (hyperalbuminemia) or Decreased (hypoalbuminemia)?
1. Inadequate source of amino acids in **malnutrition and malabsorption**
2. **Liver** disease
3. Protein losing **enteropathy or gastrointestinal loss** (diarrhea)
4. Kidney loss to urine in **renal disease**
5. Skin loss in burns or **exfoliative dermatitis**
6. **Hypothyroidism**
7. Dilution by **excess intake of water** or administration of intravenous fluids
8. **Genetic mutation** resulting from an autosomal recessive trait
9. Redistribution by **hemodilution** (e.g. sepsis)
10. Increased **catabolism** - massive **burns and malignancy**
Decreased (hypoalbuminemia)
38
# Albumin
TOF: Hyperalbuminemia has a higher clinical significance than hypoalbuminemia
False (hyperalbuminemia has no significance)
39
# Albumin
Increased (hyperalbuminemia) or Decreased (hypoalbuminemia)?
- Severe **dehydration** and **prolonged** torniquet application
Increased (hyperalbuminemia)
40
# Albumin
- An **inherited error** of albumin synthesis
- Albumin level is decreased because the **patient is not capable of synthesizing it**
Analbuminemia
41
# Albumin
- Can be **inherited or acquired**
- **2 albumin bands are present** in electrophoresis
Bisalbuminemia
42
# Serum Proteins
- Consists of **α1, α2, β and γ fractions** (through electrophoresis)
- Each consists of a number of different proteins with
different functions
Globulins
43
# Globulins
What are the 2 **negative acute phase reactants**?
Albumin and Transferrin
44
# Globulins
- The **most abundant alpha-1 globulin** (90% of the fraction)
- It neutrallizes **trypsin-like** enzymes: **Elastase** - a neutrophil protease (major inhibitor of protease activity)
- Increases in **inflammatory reactions, pregnancy, and contraceptive use**
α1-Antitrypsin (AAT)
45
# Globulins
This enzyme degrades elastin, fights infections, and can also destroy alveoli which leads to emphysema
Elastase
46
# Globulins
A mutation wherein the α1-Antitrypsin (AAT) is deficient/abnormal which causes:
- Juvenile hepatic cirrhosis
- Lung disease (emphysema); ZZ phenotype (the normal is MM)
| Elastase is increased/not inhibited
SERPINA 1
47
# Globulins
- Synthesized in the developing **embryo and fetus** and by parenchymal cells of the liver
- Protects the fetus from** immunologic attack by the mother**
- Is increased during pregnancy but will **decrease gradually after birth**, reaches adult levels by **8-12 months**
- **No known function** in normal adults
- **Tumor Marker (L3)** for liver and testicular cancer
- Screening between 15 to 20 weeks of gestation for **Neural Tube Defects and Down Syndrome**
- **Screening specimen:** Maternal serum
- **Confirmatory specimen: **Amniotic fluid
- Interpretation requires accurate dating of pregnancy
- Affected by maternal weight, race, and DM
α1-Fetoprotein (AFP)
48
# α1-Fetoprotein (AFP)
**Elevated or Decreased AFP?**
Spina bifida, neural tube defects, abdominal wall defects, anencephaly, HDN, and general fetal distress
Elevated
49
# α1-Fetoprotein (AFP)
**Elevated or Decreased AFP?**
Increased risk for Down syndrome and Trisomy 18
Decreased
50
# α1-Fetoprotein (AFP)
What are the 2 testing methods?
Radioimmunodiffusion (RID) and Enzyme-labeled Immunoassay (or ELISA)
51
# α1-Fetoprotein (AFP)
Migratory region in electrphoresis? (it lies between **2 other proteins**)
Between Albumin and A1-Globulin
52
# Globulins
- Aka **Orosomucoid**
- An **acute phase reactant**
- High percentage of **CHO** (45%) and **sialic acid** (11-12%)
- Is **negatively charged** with **low pH **
- Greatest affinity for **progesterone and binds to Quinidine** (cardioactive drug)
- Diagnostic tool for **neonates with bacterial infection**
α1-Acid Glycoprotein
53
# α1-Acid Glycoprotein
**Elevated or Decreased?**
Pregnancy, stress, inflammation and tissue damage, acute
myocardial infarction, trauma, pregnancy, cancer, pneumonia, and rheumatoid arthritis and surgery
Elevated
54
# α1-Acid Glycoprotein
What is the normal value during testing (RIA, immunofixation, and nephelometry)?
50-120 mg/dL
55
# Globulins
- **Serine proteinase inhibitor** (serpin)
- Inhibits the enzymes: cathepsin G, pancreatic elastase, mast cell chymase and chymotrypsin
- Produced by the** liver**
- An **acute phase reactant** (decreased in liver disease)
- Mutations in patients with **Parkinson's disease** and **COPD**
- **Increased** in Alzheimer's disease
α1- Antichymotrypsin
56
# Globulins
- A **serine protease inhibitor**
- Plays a role in **inflammation and carcinogenesis**
- It migrates in the **Alpha 1 and Alpha 2 interzone** (hence the name); in conventional electrophoresis, it is still part of the A1 fraction
Inter-α-trypsin Inhibitor (ITIs)
57
# Globulins
- aka **Group-specific component globulin**
- Part of the **Alpha 1 and Alpha 2 interzone**
- Carries **vitamin D**
- Transports **fatty acids and endotoxins**
- Binds with **actin** for clearing
- Co-chemotactic factor for **neutrophils and monocytes** in inflammation
- A prognostic indicator of survival with **tissue injury after trauma and hepatic failure**
Gc-globulin
58
# Gc-globulin
Elevated or Decreased?
During the third trimester of pregnancy and patients taking estrogen oral contraceptives
Elevated
59
# Gc-globulin
Elevated or Decreased?
Liver disease and protein losing syndrome
Decreased
60
# Gc-globulin
Decreased levels after **trauma/hepatic failure** indicate what prognosis?
Poor prognosis (low survival rate)
61
# Gc-globulin
What is the method of choice?
Immunonephelometry
62
# Globulins
- An **α2–glycoprotein** synthesized in the hepatocytes
- An **acute phase reactant**
- **Binds hemoglobin** to prevent urinary loss
- **3 phenotypes: **Hp1-1, Hp2-1 and Hp2-2 (increased risk for CVD in patients with DM)
- For evaluation of** anemia** (hemolytic vs. other causes); evaluate the degree of intravascular hemolysis that occurs in transfusion reactions or HDN
Haptoglobin
63
# Haptoglobin
Is it indicative of hemolytic anemia?
Decreased haptoglobin with decreased reticulocyte count
No (reticulocytes should be increased)
64
# Haptoglobin
Is it indicative of hemolytic anemia?
Normal haptoglobin with increased reticulocyte count
Yes (RBC destruction in the spleen and liver)
65
# Haptoglobin
Is it indicative of hemolytic anemia?
Normal haptoglobin with normal reticulocyte count (BUT with signs of anemia)
No (a different cause of anemia other than hemolytic)
66
# Haptoglobin
Is it indicative of hemolytic anemia?
Decreased haptoglobin without signs of anemia
No (a problem with the synthetic function of the liver)
67
- An **α2–glycoprotein** for the transport of **copper**
- Synthesized in the **liver**
- An **acute phase reactant**
- **90% or more** of total serum copper is found in this, **10%** bound in **albumin**
Ceruloplasmin
68
# Ceruloplasmin
- An **autosomal recessive** condition wherein **ceruloplasmin is low** while **tissue copper storage and urinary secretions are high** (decreased levels in the blood)
- Characterized by liver cirrhosis, CNS damage, and a Kayser-Fleischer ring in the cornea
Wilson's Disease
## Footnote
Additional: Menkes Kinky Hair Syndrome is also a copper metabolism disorder
69
# Ceruloplasmin
Methods of Determination:
Early analytic method
Copper oxidase activity
70
# Ceruloplasmin
Methods of Determination:
Immunochemical method
Radial immunodiffusion and nephelometry
71
# Globulins
- From the liver, a large protein **(major component of α2 band)**
- **Inhibits proteases** such as trypsin, pepsin, thrombin, kallikrein and plasmin by trapping (a role in hemostasis)
- Removal of **reticuloendothelial cells**
- Forms a complex with PSA (prostate specific antigen)
α2-Macroglobulin
72
# α2-Macroglobulin
Increased or Decreased?
DM, Liver disease, Nephrosis, Pregnancy, and Contraceptive use
Increased
| In nephrosis, it is 10x higher
73
# α2-Macroglobulin
Familiarize with the methods of determination
Immunodiffusion, immunonephelometry, ELISA, and latex agglutination immunoassay
74
# Globulins
- A **β-glycoprotein** synthesized by the liver
- A **negative acute phase reactant**
- Most important for the **iron pool**; transports iron to prevent urinary loss and tissue deposition
- Transports to **storage sites** (incorporated to apoferritin → ferritin)
- Reversibly binds 2 molecules of ferric iron
- Iron bound to transferrin is less than 0.1% (4 mg) of total body iron
Transferrin (Siderophilin)
75
# Transferrin (Siderophilin)
Increased or Decreased?
Impaired hemoglobin production leading to secondary iron-deficiency anemia
Decreased (iron is not recycled)
76
# Transferrin (Siderophilin)
Increased or Decreased?
Hereditary disorder in iron metabolism and hemochromatosis (iron in liver and pancreas)
- **iron overload** leads to **increased iron bound to transferrin **with tissue depletion (low transferrin)
Increased
77
# Transferrin (Siderophilin)
A hereditary condition wherein no transferrin leads to **anemia and hemosiderosis**
Atransferrinemia
78
# Transferrin (Siderophilin)
High or Low?
Iron Deficiency Anemia
High
79
# Globulins
- **β globulin**
- Synthesized by the **liver**
- An **acute phase reactant**
- A **scavenger of heme** (1:1 ratio) to protect the body from **oxidative damage** and it also preserves iron
- **Heme-Hemopexin complex** is carried to the liver for destruction
Hemopexin
80
# Hemopexin
High or Low?
Diagnostic marker of hemolytic anemia
Low
81
# Hemopexin
High or Low?
Inflammation, DM, Duchenne-type muscular dystrophy, and melanomas
High
82
# Globulins
- A light chain component of the **major histocompatibility complex class I (HLA)**
- Found on the surface of **most nucleated cells** and is present in high concentrations on **lymphocytes**
- GFR: freely filtered by the **glomerulus** but reabsorbed by **PCT**
- Is measured by immunoassays
β2 - Microglobulin
83
# Globulins
Refers to chylomicrons, VLDL, LDL, and HDL
Lipoproteins
84
# β2 - Microglobulin
High or Low?
Impaired clearance by the kidney or overproduction of the protein in rheumatoid arthritis and SLE
High
85
# Globulin
- One of the **largest proteins**
- Glycoprotein synthesized by the liver
- An acute phase reactant
- Between the **β and γ globulins**
- **Forms a fibrin clot** when activated by thrombin
- Marker for long term **prognosis of cardiovascular disease**
Fibrinogen
86
# Fibrinogen
High or Low?
Inflammation, pregnancy, and use of oral contraceptive
High
87
# Fibrinogen
High or Low?
Extensive coagulation
Low
88
# Globulins
- From the **liver**
- A **natural defense mechanism** from infection
- **Classical, Lectin, and Alternative** pathways (when activated, the membrane attack complex begins to lyse the foreign body)
- **Consumed in inflammatory reaction** (decreased)
Complement
89
# Complement
Elevated or Decreased?
Have little clinical importance
Elevated
90
Elevated or Decreased?
The complement may be consumed (e.g. in SLE and RA) or it may be decreased (malnutrition) or absent due to genetic defects
Decreased
91
# Complement
What are the 5 membrane attack complexes?
C5, C6, C7, C8, and C9
92
# Globulins
****- From the liver, it precipitates with the **C-polysaccharide** (from pneumococci)
- Migrates toward the **Beta-region (Bishop)/Gamma-region (Henry's)**
- **APR** - one of the **first to rise** in inflammation or tissue necrosis (not specific)
- **bound to bacteria** facilitates opsonization, initiates coagulation, and complement activation
- Can be used as a **screening test** to determine if the infection is bacterial or viral
- Binds with **phosphocholine and LDL**
C-Reactive Protein (CRP)
93
# C-Reactive Protein (CRP)
High or Low?
Acute infection, inflammatory disease, tissue necrosis, acute rheumatic fever, bacterial infections, myocardial infarction, rheumatoid arthritis, carcinomatosis, gout, and viral infections
High
94
# C-Reactive Protein (CRP)
- A condition that involves hsCRP
- Recurrent event in patients with unstable angina and AMI
- Low survival rate from CVD
Atherosclerosis
95
# Globulins
- Migrates toward the gamma-region
- Are not synthesized by neonates
Immunoglobulins
96
# Immunoglobulins
1. Crosses the placenta thus it comes from the mother
2. Does not cross the placenta (synthesized by the neonate upon reaching 1 year old); these are also higher in females
3. Generally higher in males (present in secretions)
4. For parasitic and allergic conditions
5. No known function
A. IgD
B. IgA
C. IgG
D. IgM
E. IgE
1. C
2. D
3. B
4. E
5. A
97
# Acute Phase Reactants
Familiarize yourself with the APRs
APRs:
- Antitrypsin
- Acid Glycoproteins
- Antichymotrypsins
- Thyroxine-binding Globulins
- A2 Macroglobulins
- Ceruloplasmin
- Haptoglobin
- LDL
- Hemopexin
- Complement
- CRP
- Fibrinogen
- Immunoglobulins
98
# Patterns of Electrophoresis
Immediate Response Graph:
What regions increase and what decrease?
(2 answers)
Increased: A2 region (an APR)
Decreased: Albumin region (a negative APR)
99
# Patterns of Electrophoresis
Delayed Response Graph:
What regions increase and what decrease?
(3 answers)
Increased: A2 region (haptoglobin: an APR) and Gamma Region (IgG)
Decreased: Albumin
100
# Patterns of Electrophoresis
Hypogammaglobulinemia Graph:
What region decreases?
Gamma region (gammaglobulins in the blood)
## Footnote
Occurs in neonates (not yet capable of producing antibodies), undergoing chemotherapy, immunocompromised, lymphoreticular disorders, or agammaglobulinemia (total absence)
101
# Patterns of Electrophoresis
Hepatic Cirrhosis/Polyclonal Gammopathy Graph:
What regions increase and decrease?
(2 answers)
Increased: Gamma region (beta-gamma bridging); all immunoglobulins are INCREASED
Decreased: Albumin region (the liver produces albumin)
102
# Patterns of Electrophoresis
Multiple Myeloma/Paraprotein/Monoclonal Gamopathy Graph:
What regions increase and decrease?
(2 answers)
Increased: Only specific immunoglobulins (variable for multiple myeloma)
Decreased: Albumin region
| Multiple myeloma: Elevated B-cells/plasma cells
103
# Patterns of Electrophoresis
In macroglobulinemia, what immunoglobulin is elevated?
IgM
104
# Patterns of Electrophoresis
Nephrotic Syndrome Graph:
What regions increase and decrease IN BLOOD?
(3 answers)
Increased: A2 Macroglobulins (large protein)
Decreased: Albumin and other regions
## Footnote
Decreased because kidney is damaged therefore these analytes are excreted
105
# Patterns of Electrophoresis
Nephrotic Syndrome Graph:
What regions increase and decrease IN URINE?
Increased: Albumin and other regions
Decreased: A2 Macroglobulins (large protein)
| Reverse of nephrotic syndrome blood levels
106
# Patterns of Electrophoresis
Protein-losing Enteropathy Graph:
What regions increase and decrease?
(4 answers)
## Footnote
Protein-losing = absorption problem
Increased: Haptoglobin and A2 Macroglobulin
Decreased: Albumin and Gamma-region
