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Chapter 7 The Plasma Protein

Chapter 7 The Plasma Protein. Tu Jiancheng. contents. 1. Concept of Plasma Protein 2. Total Protein: Acute-phase Reactants Individual Proteins and Disease States 3. Methods of Protein Analysis. 1. Concept of Plasma Protein.

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Chapter 7 The Plasma Protein

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  1. Chapter 7 The Plasma Protein Tu Jiancheng

  2. contents 1. Concept of Plasma Protein 2. Total Protein: Acute-phase Reactants Individual Proteins and Disease States 3. Methods of Protein Analysis

  3. 1. Concept of Plasma Protein The Plasma Proteins Are A Diverse Group of Molecules That Perform A Variety Of Functions * Need to Be Distinguished from Proteins That Occur Only Incidentally in The Blood. * Often Classified Based on Their Electrophoretic Mobility * Most of Them are Synthesized in the liver

  4. Densitometric scan of a normal serum protein electrophoresis pattern showing the relative position of the albumin,α1,α2,β and γregions

  5. Selected Majora and Minor Plasma Proteins (TABLE 7-2 ) a In boldface

  6. Plasma protein abnormalities arise from one or more of the following: * Congenital abnormalities affecting a specific protein * Acquired abnormaltities affecting a specific protein * Alterations affecting multiple proteins reflecting variations in the physiologic state * Alterations affecting multiple proteins secondary to disease

  7. 2. Total Protein Factors Which Affect Protein Concentration: * Fluid Balance * Changes in Synthesis or Catabolism * Protein losses.

  8. Preanalytic Errors Which May Alter the Serum Protein value * Prolonged Tourniquet Application during Venipuncture Increase the Total Protein by as much as 5g/L. * Recumbent Subjects 10% lower than in Ambulatory Ones * Normal Diurnal Variation of 4 g/L * Seasonal Fluctuation: Peak in Nov. and Lowest in June. * Exercise increases the serum protein concentration by as much as 10%, but this effect is transient.

  9. * The total serum protein includes both albumin (60%) and the globulins (40%) * The total protein concentration may be altered by changes in fluid balance * Changes in the amounts of plasma proteins may result from alterations in synthesis or catabolism or from protein losses

  10. Hypoproteinemia * decreased protein synthesis * malnutrition * chronic liver disease Nephritic syndrome * the serum albumin level may fall to less than 5 g/L

  11. ACUTE-PHASE REACTANTS(APRs) A Group of Proteins Whose Plasma Concentration Changes In Response To A Variety of Inflammatory Sates Including: * Infection * Surgery * Trauma * Myocardial Infarction * Malignancy * Any Condition Associated with Tissue Necrosis

  12. Regulation of APRs Cytokines * Major Stimulator: Interleukin-6 (IL-6) is the * Other Cytokins Which Upreugulate APRs: Interleukin-1β(IL-1β), Tumor Necrosis Factor-α(TNF-α) Interferon Gamma (IFN-γ) Transforming growth factorβ(TGF-β)

  13. Major Acute Phase Reactants(TABLE 7-3 )

  14. * Measurement of APRs, especially C-reactive protein (CRP), may be useful to detect and follow patients with acute inflammatory disorders.

  15. The changes in plasma proteins seen during the acute-phase response potentially serve a variety of functions * Positive APRs: AAT,α1-Antichymotrypsin. * Protect against reactive oxygen species: haptoglobin, hemopexin

  16. Individual Proteins and Disease States Prealbumin Albumin α1-Antitrypsin α2-Macroglobulin Ceruloplasmin Haptoglobin Transferrin β-Lipoprotein β2-Microglobulin C-Reactive Protein

  17. * Prealbumin is a tryptophan-rich tetrameric non-glycosylated protein named for its anodal migration relative to albumin on protein electrophoresis. Prealbumin(1)

  18. Prealbumin(2) [MW]: 55 kD [Synthesized]: in Liver [Synonyms]: Transthyretin and Thyroid-Binding Prealbumin. [Function]: Carrier Protein for Thyroid Hormone and for vitamin A (with Retinal Binding Protein) [Half-Lives]: 1.9 days. [Reference Range]: 195 - 358 mg/L

  19. * Prealbumin levels reflect hepatic synthesis and can serve as an index of liver function * Prealbumin is a compact molecule that can cross the blood-brain barrier and may also be synthesized by cells of the choroids plexus. * Prealbumin can be measured by a variety of immunoassays, including radial immunodiffusion and nephelometry.

  20. Albumin(1) The most abundant protein in plasma, comprising approximately 60% of the total protein concentration.

  21. Albumin (2) [MW] 66.3kD, Most Abundant protein in Plasma, [Synthesized] almost exclusively by the liver, [Half-life] 19 days. [Functions]1. 80% of the plasma COP. 2. Amino Acid Source to a Variety of Cells 3. Major Transport Protein 4. Lipid Metabolism [Reference Range] 31 to 43g/L.

  22. [measure] Electrophorectic Immunochemical dye-binding techniques bromocresol purple Bromocresol green Albumin(3)

  23. α1-Antitrypsin (AAT)(1) One of the major plasma proteins, comprising nearly 90% of the α1 globulin region on SPE. Deficiency of AAT has been associated with pulmonary emphysema and hepatic cirrhosis.

  24. α1-Antitrypsin (AAT)(2) • [MW]: 52kD, Major Plasma Proteins, • [Function]: a Serine Proteinase Inhibitors(Serpins ) • [Synthesizied]: in Liver. Seen in Plasma, Tears, Lymph, Bile, • Semen, and Amniotic • [Acquired decreases]: • Protein-losing syndromes, • malnutrition, • severe liver damage, • respiratory diseases: neonatal respiratory distress syndrome • [Congenital Deficiency]: • Pulmonary Emphysema and Hepatic Cirrhosis • [Reference Range]: 900~1500mg/L

  25. * Genes encoding the AAT protein comprise an autosomal allelic system containing at least 75 codominant genes inherited on a single locus called Pi for proteinase inhibitor. α1-Antitrypsin (AAT)(3)

  26. The PiZ allele is the most common variant associated with AAT deficiency. PiZZ : 10% to 15% (normal) PiMZ: 60% (normal) PiSS and PiMS: 63% and 83%(normal) α1-Antitrypsin (AAT)(4)

  27. * Consists of four identical subunits and is one of the largest serum proteins * Can inhibit Several endopeptidases * Can bind numerous growth factors, hormones, and cytokines α2-Macroglobulin(AMG)(1)

  28. α2-Macroglobulin(AMG)(2) [MW] 720 kD, Largest Serum Protein [Synthesized] in Liver [Half Life] 5 Day in Serum [Function] 1. Defense Against Proteolytic Enzymes (Irreversibly Binds Proteinases ) 2. Transport Protein? (Binds to Growth Factors, Hormones, and Cytokines) [Reference Range]125 to 215 mg/dL

  29. Ceruloplasmin(CER)(1) * A glycoprotein synthesized by the liver as a single polypeptide chain to which six to eight copper atoms are attached. * The pure protein is blue because of its high copper content. Increased levels may impart a green tinge to plasma samples.

  30. Ceruloplasmin(CER)(2) [MW] 132kD, a Glycoprotein, Synthesized by the Liver, not Normally Visible on Routine Gels [Clinical Significants]: Diagnosis of Wilson’s Disease (Hepatolenticular Degenetation) [Reference Range]: 27 to 50 mg/dL Highest in young children and somewhat Lower in both Infants and Adults. Less than 10 mg/dL are Suggestive of Wilson’s Disease,

  31. Haptoglobin(1) * A glycoprotein synthesized by the liver that migrates as an α2 globulin. * In addition to its well-known function in the binding of free hemoglobin, this APR might also play an important role in the control of local inflammation.

  32. Haptoglobin(2) Glycoprotein [Synthesized] in the liver [Migrates] as α2 globulin [Function] Binding of Free Hemoglobin, Control of Local Inflammation. [Clinical Significatns] Decreased Associated with Intravascular Hemolysis, (Hemolytic Anemias, Hemoglobin-opathies, Hemolytic Transfusion Reactions, Extensive Burns, Malaria, Disseminated Intravascular Coagulation, and Exercise-Induced Hemolysis). [Reference range] 16 to 199 mg/dL.

  33. Transferrin [MW]: 80kD, a Glycoprotein [Synthesized] by Liver(most), reticuloendothelial system, the gonads, and the submaxillary gland [Function] Transport of Iron from Intestine (or Hemoglobin catabolism) to Red Cell [Reference Range] 191 to 365 mg/dL (1.91 to 3.65g/L).

  34. β-Lipoprotein(1) * Lipoproteins constitute a family of molecules composed of lipids and proteins whose function is to transport cholesterol, triglycerides, and phospholipids in the blood.

  35. β-Lipoprotein(2) [Components] Chylomicrons(CM), [Very Low Density Lipoproteins (VLDL) [Low-Density Lipoproteins (LDL) [High-Density Lipoproteins (HDL).

  36. β2-Microglobulin(1) * A small protein (MW 11,818) comprising the common light chain of the class I major histocompatibility complex antigen on the surfaces of all nucleated cells.

  37. β2-Microglobulin(2) [MW] ~11,818 Dalton, Noncovalently Linked to the human lymphocyte antigen (HLA) heavy chain. [Distribution] Plasma, Urine, and CSF [Function] Necessary for Insertion of the HLA into Cell Membrane, and Stabilize the HLA heavy chain. It Regulation of Some Lymphocyte Functions. [The normal Reference Range] Serum 2.8mg/L Urine 0.2mg/L

  38. * CRP was first identified in 1930 as a substance present in the sera of patients with pneumococcal pneumonia that could bind to C-polysaccharide isolated from Streptococcus pneumoniae, producing a flocculation reaction. C-Reactive Protein(CRP)(1)

  39. C-Reactive Protein(CRP)(2) [MW] 118,000 Dal [Physiology] Elevated in a Variety of Acute Inflammatory siseases. [Half Life] 19 hours. [Synthesized] by the liver and released into the plasma. Peripheral(Small Amount) [Function] Recognition of Microbial Organisms An immunomodulator in Host Defense. Recognition of Necrotic Tissues. [Reference Range] Less than 0.8mg/dL..

  40. MTEHODS OF PROTEIN ANALYSIS * Measurement of Total Protein * Serum Protein Electrophoresis * Other methods

  41. Measurement of Total Protein ☆Kjeldahl procedure ☆ biuret method ☆ Lowry method ☆ dye-binding procedures ☆ turbidimetric method ☆ nephelometric method

  42. Serum Protein Electrophoresis * Principles of Electrophoresis * Agarose Gel Electrophoresis * Capillary Elecrophoresis

  43. Principles of Electrophoresis ＊ support media ＊ buffer ions ＊ pH ＊ the size and shape of the molecule ＊ the strength of the electric field ＊ the temperature ＊ the effects of convection and diffusion ＊ the ionic and pore properties of the ＊ electrophoresis medium

  44. Typical serum protein Electrophoresis Reference Pattern (TABLE 7-4)

  45. Representative patterns of serum protein seen on serum protein electrophoresis

  46. Capillary Elecrophoresis * Electrophoretic separation of analytes is carried out in fused-silica capillaries with an inner diameter of 50 μm (range, 20 to 200 μm), an outer diameter of 375 μm, and an effective length of approximately 50 cm (range, 7 to 100 cm).

  47. Other Methods * Ion Exchange Chromatogrphy * Affinity Chromatogrphy * Isoelectric Focusing

  48. Thanks!

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