Plasma protein

Plasma proteins is a collective term for the most common blood proteins found in blood plasma . Their total concentration is 60–80 g / l. If these proteins are separated by means of electrophoresis , albumins and globulins are obtained . The latter are divided into four subclasses (α ₁ -, α ₂ -, β and γ globulins) according to their electrophoretic mobility . The main ones are glycoproteins , lipoproteins and metalloproteins . Their molecular mass is 67  kDa for albumins and between 67 kDa and 1.3 MDa for globulins.

Plasma proteins perform numerous tasks in blood plasma. This includes maintaining the colloid osmotic pressure and the blood pH value (buffer function) and the transport (specific and unspecific carriers ) of water-insoluble substances, hormones and enzymes . They also play an important role in homeostasis and blood coagulation (as components of the complement system , as plasma protease inhibitors and as acute phase proteins ), the immune system ( immunoglobulins ) and in the course of inflammation .

Selected plasma proteins

• Albumins (60%)
• Globulins (40%)
  • α ₁ -globulins (4%)
    • Transcortin (→ steroid transport)
    • α ₁ -antitrypsin (→ protease inhibitor )
    • α ₁ -antichymotrypsin (→ protease inhibitor )
    • α-lipoprotein ( HDL ) (→ transport of blood lipids)
    • Prothrombin (→ proenzyme of thrombin)
    • Transcobalamin (→ transport of cobalamin)
  • α ₂ - globulins (8%)
    • Haptoglobin (→ binding and transport of hemoglobin )
    • α ₂ -macroglobulin (→ anticoagulant)
    • α ₂ -antithrombin (→ anticoagulant)
    • Ceruloplasmin (→ copper transport, ferrooxidase)
  • β-globulins (12%)
    • Transferrin (→ iron transport)
    • β-lipoprotein ( LDL , VLDL ) (→ transport of blood lipids)
    • Fibrinogen (→ blood clotting factor)
    • Hemopexin (→ binding of free heme)
  • γ-globulins (16%)
    • Immunoglobulins (antibodies) ( IgA , IgD , IgE , IgG , IgM )

literature

• Anderson NL and Anderson NG (1977). "High Resolution Two-Dimensional Electrophoresis of Human Plasma Proteins". Proceeding of the National Academy of Sciences 74 (12): 5421-5425. doi : 10.1073 / pnas.74.12.5421 . PMC 431746 (free full text). PMID 271964 .
• Adkins JN et al. (2002). "Toward a human blood serum proteome: analysis by multidimensional separation coupled with mass spectrometry". Molecular and Cellular Proteomics 1 (12): 947-955. doi : 10.1074 / mcp.M200066-MCP200 . PMID 12543931 .
• Jacobs JM et al. (2005). "Utilizing human blood plasma for proteomic biomarker discovery". Journal of Proteome Research 4 (4): 1073-1085. doi : 10.1021 / pr0500657 . PMID 16083256 .
• Jeremy M. Berg, John L. Tymoczko, Lubert Stryer : Biochemistry. 6 edition, Spektrum Akademischer Verlag, Heidelberg 2007. ISBN 978-3-8274-1800-5 .
• Donald Voet, Judith G. Voet: Biochemistry. 3rd edition, John Wiley & Sons, New York 2004. ISBN 0-471-19350-X .
• Bruce Alberts , Alexander Johnson, Peter Walter, Julian Lewis, Martin Raff, Keith Roberts: Molecular Biology of the Cell , 5th Edition, Taylor & Francis 2007, ISBN 978-0815341062 .