Plasma Proteins Reading assignment Harper

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Plasma Proteins Reading assignment Harpers
Biochemistry PP 737-745

• Dr. Zeyad El-Akawi Jreisat, M.D, M.A, Ph.D

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Blood

• Solid elements
• Red cells
• White cells
• Platelets
• Liquid medium
• Plasma

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Blood
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Major Functions of Blood

• - Respiration
• - Nutrition
• - Excretion
• - Acid-base balance
• - Water balance
• - Body temperature regulation
• - Defense
• - Hormone transport and regulation of metabolism
• - Metabolite transport
• - Coagulation

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Difference between plasma and serum????

• Serum plasma - coagulation factors

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Plasma Composition

• Water 92
• Plasma proteins 7 (total 7.0-7.5 g/dL)
• Simple
• Conjugated
• Glycoproteins
• Lipoproteins
• Electrolytes (Na, K, Ca2, Cl-, HCO3-)
• Metabolites
• Nutrients
• Hormones
• Other solutes 1

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Plasma proteins

• Most plasma proteins, with the exception of
  immunoglobulins and protein hormones are
  synthesized in the liver
• Plasma proteins are generally synthesized on
  membrane-bound polyribosomes
• Rough endoplasmic membrane ? smooth endoplasmic
  membrane ? Golgi apparatus ? secretory vesicles ?
  Plasma
• Almost all plasma proteins are glycoproteins
• Plasma proteins circulate in the blood and
  between the blood and the extra-cellular tissue
  spaces. Their movement occurs not only by passive
  diffusion through junctions between capillary
  endothelial cells but by active transport
  mechanisms and by pinocytosis and exocytosis

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Plasma proteins

• Because of this movement, most extra-vascular
  fluids normally contain small amount of plasma
  proteins
• The concentration of protein in the plasma is
  important in determining the distribution of
  fluid between blood and tissues
• Many plasma proteins exhibit polymorphism
• Alpha1-antitrypsin, haptoglobin, transferrin,
  ceruloplasmin and immunoglobulins
• Each plasma protein has a characteristic
  half-life in the circulation
• Most plasma proteins are catabolized in the
  liver.

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Plasma proteins

• Alterations in plasma proteins occurs in health
  and disease
• The levels of certain proteins in plasma increase
  during acute inflammatory states or secondary to
  certain types of tissue damage
• Some of these alterations have genetic origin,
  many more reflect physiological or pathological
  processes
• Variations in the amount or kinds of protein
  found in plasma or extra-vascular fluids depend
  on many factors
• Genetic
• Physiological
• Pathological

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Classification of plasma proteins based on their
function

• Antiproteases antichymotrypsin,
  alpha1-antitrypsin, alpha2-macroglobulin,
  antithrombin
• Blood clotting various coagulation factors,
  fibrinogen
• Enzymes
• Function in blood coagulation factors,
  cholinesterase
• Leakage from cells or tissues aminotransferases
• Hormones Erythropoietin
• Immune defense immunoglobulins, complement
  proteins, beta2-microglobulin
• Involvement in inflammatory responses Acute
  phase response proteins (c-reactive proteins,
  alpha1-acid glycoprotein)
• Oncofetal alpha-1 fetoprotein (AFP)

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Classification of plasma proteins based on their
function

• Transport or Binding proteins
• Albumin various ligands, including bilirubin,
  free fatty acids, ions (Ca2), metals (Cu2,
  Zn2), metheme, steroids and other hormones,
  drugs.
• Ceruloplasmin contains Cu2
• Corticosteroid-binding globulin transcortin
  (binds cortisol)
• Haptoglobin binds extracorpuscular hemoglobin
• Lipoproteins chylomicrons, VLDL, LDL, HDL
• Hemopexin binds heme
• Ritenol-binding protein binds retinol
• Sex hormone-binding globulin binds testosterone,
  estradiol
• Thyroid-binding globulin binds T3, T4
• Transferrin transport iron
• Transthyretin (prealbumin) binds T4 and forms a
  complex with retinol-binding protein

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Plasma proteins separation

• Separation of individual proteins from a complex
  mixture is accomplished by the use of solvents or
  electrolytes or both to remove different protein
  fractions in accordance with their solubility
  characteristics.
• Salting out a method for separation of plasma
  proteins using various concentrations of
• Sodium or ammonium sulfate
• Plasma proteins can be separated by this method
  into three groups
• Fibrinogen
• Albumin
• Globulins

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Plasma proteins separation

• Electrophoresis
• The most common method of analyzing plasma
  proteins
• Using different supporting medium, the most
  common in clinical laboratories is cellulose
  acetate (electrophoretogram)
• Separated proteins into five bands albumin,
  alpha1, alpha2, beta, and gamma fractions
• The amount of bands quantified by densitometric
  scanning machine

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Electrophoresis
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Plasma protein electrophoresis
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Quantified of plasma proteins by densitometric
scanning machine
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(No Transcript)
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Plasma proteins separation

• Antibodies
• Specific plasma proteins are separated by
  specific monoclonal antibodies fixed on
  stationary phase
• (Column Chromatography)
• Allowing isolation of pure proteins from the
  complex mixture present in plasma

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Acute phase reactant proteins

• Concentration of these proteins rise
  significantly in acute inflammation, chronic
  inflammation and cancer
• Alpha1-antitrypsin (AAT) congenital deficiency
  may be associated with emphysema or cirrhosis
• Alpha1-acid glycoprotein (AAG) binds cationic
  drugs and hormones
• Haptoglobin (HAP) binds hemoglobin, reduced by
  hemolysis
• Ceruloplasmin (CER) contains copper,
  antioxidant, decreased in Wilsons disease
• C4 Complement factor
• C3 Complement factor
• C-reactive protein (CRP) Nonspecific defense
  against infectious agents
• Fibrinogen
• Stimulatory factors, Interleukin-1 (IL-1) and
  interleukin-6 (IL-6) at the gene level

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Plasma proteins

• Albumin
• is the major protein of human plasma (3.4-4.7
  g/dL)
• Approximately 40 of albumin is present in plasma
  and the other 60 in the extracellular space
• It synthesized in the liver as preproprotein
• The synthesis of albumin is depressed in a
  variety of diseases, particularly those of the
  liver (decreased albumin/globulin ratio)
• Responsible for 75-80 of the osmotic pressure of
  human plasma
• Absence of albumin (analbuminemia) might caused
  by mutation that affect splicing
• It binds many ligands (free fatty acids, calcium,
  certain steroid hormones, bilirubin, tryptophan)
• It binds and transport drugs (sulfonamides,
  penicillin G, dicumarol, aspirin)
• It transports copper

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• Haptoglobin
• Binds extracorpuscular hemoglobin preventing free
  hemoglobin from entering the kidney
• Exist in three polymorphic forms, Hp1-1, Hp2-1,
  Hp2-2
• Low levels of haptoglobin are found in patients
  with hemolytic anemias
• It is an acute phase protein and its plasma level
  is elevated in a variety of inflammatory states
• Transferrin
• Is a beta-1 globulin
• It is a glycoprotein synthesized in the liver
• Shuttles iron to sites where it is needed
• Transferrin diminishes the potential toxicity of
  iron
• The concentration of transferrin in plasma is
  approximately 300 mg/dL that can bind 300 µg of
  iron per deciliter (total iron-binding capacity)
  of plasma

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• Ferritin
• Normally there is a little ferritin in human
  plasma
• In patients with excess iron, the amount of
  ferritin in plasma is markedly elevated
• Index of body iron stores
• Synthesis of the transferrin receptors and that
  of ferritin are reciprocally linked to cellular
  iron content
• Iron response elements
• Iron-responsive element-binding protein
• Hemosiderin
• Partly degraded form of ferritin but still
  containing iron
• Primary hemochromatosis is a common genetic
  disorder characterized by excessive storage of
  iron in tissues leading to tissue damage
• Secondary hemochromatosis can occurs in the
  result of increased iron levels by transfusion,
  intake, hemolysis

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• Ceruloplasmin
• It is an alpha-2 globulin
• Binds copper
• Low levels of this protein are associated with
  Wilson disease
• It exhibits a copper-dependent oxidase activity
• Copper
• Is a cofactor for certain enzymes including,
  amine oxidase, copper-dependent superoxide
  dismutase, cytochrome oxidase, tyrosinase
• It is excess can cause problems because it can
  oxidize proteins and lipids, bind to nucleic
  acids and enhance the production of free radicals
• Metallothioneins are a group of small proteins
  found in the cytosol of cells particularly of
  liver, kidney, and intestine they control of
  copper levels

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• Menkes Disease kinky or Steely hair disease
• Is due to mutations in the gene for a
  copper-binding P-type ATPase leads to abnormality
  in copper metabolism
• X-linked
• Defect in copper exit from cells leads to its
  accumulation
• Involves the nervous system, connective tissue
  and vasculature
• Wilson Disease
• Is due to mutations in the gene for a
  copper-binding P-type ATPase results in the
  failure of copper to be excreted in the bile
• Copper toxicoses
• Alpha-1 antitrypsin deficiency a serine protease
  inhibitor
• Is associated with emphysema and liver disease
• Synthesized by hepatocytes and macrophages