1. Dr. Nasim AP Biochemistry
Plasma Proteins
Dr. Nasim
AP Biochemistry

2. Plasma Proteins Synthesized by liver or produced by plasma (B) cells
Albumin
Transferrin
Ceruloplasmin
Enzymes – Coagulation enzymes, complement factors
C-reactive protein – Acute phase reactant
Immunoglobulins – Humoral immunity
Transport proteins

3. ALBUMIN 66 kDa Accounts for ~50% of the total plasma protein and ~ 50%
of the total liver protein production
 Half-life ~ 20 days
 Highly polar
 At pH 7.4 it is anionic with 20 negative charges per molecule

4. Causes of Decreased Plasma Albumin:
Decreased synthesis
A. Malnutrition
B. Malabsorption
C. Advanced chronic liver disease
II. Abnormal distribution or dilution
A. Overhydration
B. Increased capillary permeability like in
septicemia
Abnormal excretion or degradation
A. Nephrotic syndrome
B. Burns
C. Hemorrhage
D. Certain catabolic states
E. Loss of protein from the digestive tract
Rare congenital defects
A. Hypoalbuminemia

5. Regulation of Colloidal Pressure
Gaw: Clinical Biochemistry; Churchill Livingstone (1999), p. 44.

6. Plasma Proteins Globulins Fibrinogen 36% of plasma proteins
alpha and beta produced in liver
proteins that bind to lipids, metal ions and fat-soluble vitamins
gamma - antibodies produced by plasma cells during immune response
Fibrinogen
4% of plasma proteins
produced in liver
forms fibrin threads during clotting

7. TRANSFERRIN
Transports iron in plasma as ferric ions (Fe3+) – each Transferrin molecule binds 2 Fe3+
Protects the body against the toxic effects of free iron
Normally 30% saturated with Fe3+ - increased or decreased saturation is indicative of iron overload or deficiency, respectively
 Decreased in inflammatory states due to excessive degradation of Transferrin- Fe3+ complexes

8. CERULOPLASMIN Major copper transport protein
 Regulates oxidation-reduction, transport and utilization of iron
Increased concentrations are found in active liver disease or tissue damage
Decreases are sometimes observed in individuals with Wilson’s disease

9. Plasma Proteins Functions
1. Maintaining colloid osmotic balance (albumins) 2. Buffering pH changes 3. Transport of materials through blood (such as water insoluble hormones) 4. Antibodies (e.g. gamma globulins, Immunoglobulins) 5. Clotting factors (e.g. fibrinogen)