Plasma Proteins

• Total blood plasma protein concentration – Approximately 7.5 g/dl (6.4- 8.3 gm/dl).
• Classified into,
• Albumin (4.8 gm/dl).
• Globulins (2.3 gm%).
• Fibrinogen (0.3 gm%).

FUNCTIONS:

1.Osmotic pressure:

• Determined by no. of solute particles in solution.
• Albumin – Most important contribution to oncotic pressure (compartive to globulin).

Reasons:

• Increased total albumin concentration.
• Smaller molecular weight.
• Albumin contains greater number of particles than globulin per gram weight.

2. Blood viscosity

3. Coagulation & fibrinolysis:

• Most clotting & fibrinolytic factors are proteins.

4. Buffer actions:

• With presence of COOH & -NH2 radicals.
• Acts as weak acids and & bases respectively.

5. Defense mechanism:

• Includes “Immunoglobulins” & complement system proteins.

6. Carrier proteins:

• Act as carriers of metals, hormones, lipid & drugs.

6a. Albumin – 

• Transports,
• FFA.
• Bilirubin.
• Steroid hormones.
• Calcium.
• Copper.
• Drugs.

6b. Pre-albumin –

• Transports, 
• Thyroxine.
• Vitamin A.

• α1-lipoprotein – Transport of cholesterol & phospholipids.
• Retinol-binding protein – Vitamin A transport.
• Thyroxine-binding protein – Thyroid hormone transport.
• Transcortin – Adrenal steroids transport.

6d. Alpha-2 globulin:

Haptoglobin –

• Binds to hemoglobin.
• Prevents its renal excretion.

Ceruloplasmin –

• Binds to copper.

6e. Beta-globulins:

• β-lipoproteins – Transport of triglyceride & cholesterol (I.e., Chylomicrons).
• Transferrin – Iron transport.

 PLASMA PROTEINS

FUNCTIONS:

1.Osmotic pressure:

• Albumin – Most important contribution.

Reasons:

• Increased total albumin concentration. 
• Smaller molecular weight .

2. Defense mechanism:

• Includes “Immunoglobulins” & complement system proteins.

3. Carrier proteins:

• Acts a carrier of metals, hormones, lipid & drugs.

Albumin –

• Transport of FFA.

Pre-albumin –

• Thyroxine transport & Vitamin A.

Haptoglobin –

• Binds to hemoglobin.

Ceruloplasmin –

• Binds to copper.

β-lipoproteins – 

• Transport of triglyceride & cholesterol (I.e., Chylomicrons).

Transferrin – 

• Iron transport.