blood: cells and plasma proteins beth a. bouchard bioc 212: biochemistry of human disease spring...
Post on 20-Dec-2015
220 views
TRANSCRIPT
Blood: Cells and Plasma Proteins
Beth A. BouchardBIOC 212: Biochemistry of Human Disease
Spring 2006
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
Red Blood Cells(Erythrocytes)
1011 produced per day
Lack a nucleus and intracellular organelles (incapable of protein synthesis and repair)
Contain specific proteins and ions
Transport oxygen, and remove CO2 and H+
Finite life span of 60-120 days beforebeing destroyed in the spleen
150-400 x 106/mL blood
Normal subcellular structures except they lack a nucleus
Capable of mitochondrial protein synthesis
Circulate in a non-functional state
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
Platelets
2 – 3 um
Plasma proteins
Synthesized by liver or produced by plasma (B) cells
A. AlbuminB. TransferrinC. CeruloplasminD. Enzymes – coagulation enzymes, complement factorsE. C-reactive protein – acute phase reactantF. Immunoglobulins – humoral immunity
Transport proteins
66 kDa
ALBUMIN
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
Causes of decreased plasma albumin:I. Decreased synthesis
A. malnutrtionB. malabsorptionC. advanced chronic liver disease
II. Abnormal distribution or dilutionA. overhydrationB. increased capillary permeability like in septicemia
III. Abnormal excretion or degradationA. nephrotic syndromeB. burnsC. hemorrhageD. certain catabolic statesE. loss of protein from the digestive tract
IV. Rare congenital defects A. hypoalbuminemia B. analbuminemia
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
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
ENZYMES
Enzymes of the coagulation and complement cascade have a defined function in blood
Other enzymes reside elsewhere in the body and appear incidentally in the blood – their measurement is of diagnostic value
Acid phosphatase Amylase
Creatine kinaseAlanine
aminotransferase
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