1. Blood: Cells and Plasma Proteins
Beth A. Bouchard
BIOC 212: Biochemistry of Human Disease
Spring 2005

2. I. Major functions of blood and its components:
 transport and distribution of essential nutrients to tissues
 removal of waste products
 defense against internal insult
 repair of damaged tissues
II. Two major components of blood: liquid phase and formed elements

3. Plasma
“Buffy coat”
Red blood cells
Buffy coat
Plasma - blood treated with anticoagulants to prevent clot formation then centrifuged to remove the cells Serum - blood that is allowed to form a fibrin clot then centrifuged to remove the cells and the clot

5. Red Blood Cells (Erythrocytes)  1011 produced per day  Anucleate
 Lack intracellular organelles (incapable of
protein synthesis and repair)
 Contain specific proteins and ions
 Transport oxygen, and remove CO2 and H+
 Finite life span of days before
being destroyed in the spleen

7. Platelets  2-3 mm in diameter  150-400 x 106/mL blood
Normal subcellular structures except they lack a nucleus
Capable of mitochondrial protein synthesis
 Platelet function is dependent upon their activation
 Involved in blood clotting
Contain secretory organelles called alpha-granules, which contain proteins important in blood clotting
Circulate for 10 days before being destroyed

10. 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

11. 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

12. Functions of Albumin  Transport of long chain fatty acids & sterols
 Transport of bilirubin
 Binding and solubilization of drugs

13. Regulation of colloidal pressure
Decreases in albumin concentration cause edema
Gaw: Clinical Biochemistry; Churchill Livingstone (1999), p. 44.

14. Causes of decreased plasma albumin:
Decreased synthesis
A. malnutrtion
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. protein losing enteropathies
Rare congenital defects
A. hypoalbuminemia
B. analbuminemia

15. 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

16. 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

17. ENZYMES
 Enzymes of the coagulation and complement cascade have a defined function in blood
 Others reside elsewhere in the body and appear incidentally in the blood – their measurement is of diagnostic value
Creatine kinase
Alanine
aminotransferase
Acid phosphatase
Amylase

18. C-REACTIVE PROTEIN (CRP)
 Major component of the acute phase response and a marker of bacterial infection
 Mediates the binding of foreign polysaccharides, phospholipids and complex polyanions, as well as the activation of complement
 <1 mg/mL in normal plasma
Slightly elevated levels of CRP are indicative of chronic, low-grade inflammation and have been correlated with an increased risk of cardiovascular disease

20. IMMUNOGLOBULINS
Proteins produced and secreted by B cells specific for the foreign particle that stimulated their synthesis
Five classes of Ig
Multiple myeloma: arises from the aberrant proliferation of a single B cell. Light chains of Igs are produced in excess of heavy chains = paraproteins.
Elevated serum protein levels are usually due to an increase in the Ig fraction and may indicate the presence of a paraprotein.