Globulins

Globulins are storage proteins of plants and proteins of the blood plasma of animals . However, albumin is the only blood protein that does not belong to the globulins. Globulins belong to the group of globular proteins . The main place where globulins are formed is the liver . In the blood plasma they make up about 40% of the total protein, their mass is between 36  kDa and 1.3 MDa. Globulins clump together at 60 ° C, and they are denatured by precipitants . They are broken down by enzymes and by hydrolysis .

Globulins are proteins that are insoluble in water and that are treated with dilute neutral salt solutions, e.g. B. ammonium sulfate solution can be dissolved. They have numerous functions, including as enzymes , in pH regulation, as energy suppliers, transporters and in hemostasis . Their main task, however, is to be seen in the natural and acquired immunity to foreign bodies. The immunologically active globulins are known as immunoglobulins and their synthesis takes place in plasma cells .

According to their electrophoretic mobility, they are divided into four groups:

• α ₁ -Globulins
  • Transcortin ( steroid transport)
  • Transcobalamin ( vitamin B ₁₂ binding)
  • Thyroxine- binding globulin
  • Bilirubin transporter
  • Prothrombin (proenzyme of thrombin )
  • Gc globulin ( vitamin D binding)
  • α ₁ -antitrypsin

• α ₂ -globulins
  • α ₂ haptoglobin : hemoglobin binding
  • Caeruloplasmin : transport of copper ions
  • Plasminogen
  • α ₂ macroglobulin
  • α ₂ antithrombin
  • Fetuins

• β-globulins
  • Lipid- transporting beta- lipoproteins : lipid transport
  • Transferrin : iron transport
  • Fibrinogen : precursor to fibrin
  • Hemopexin : Häminbindung and transport
  • C-reactive protein : Acute phase protein

• γ-globulins
  • Immunoglobulins (antibodies) ( IgA , IgD , IgE , IgG , IgM )

literature

• 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 .
• Speckmann, Hescheler, Köhling: Physiologie 6th edition, Urban & Fischer, Munich 2013. ISBN 978-3-437-41319-3