Lipopolysaccharide

Lipopolysaccharides (LPS ) are relatively thermostable ( heat- resistant ) compounds from fat-like ( lipo ) ingredients and sugar constituents ( polysaccharides ). They are contained in the outer membrane of gram-negative bacteria. They act as antigens and are used for serological characterization and identification of the bacteria. When the bacteria disintegrate parts of it freely and toxic. These parts are referred to as endotoxins and is not discharged from intact bacteria.

Structure

Lipopolysaccharide composed of three portions, which are interconnected:

  • Lipid A
  • Core region
  • Polysaccharide

The polysaccharide chains can be very short or absent. Absence of the core region does not occur.

Biosynthesis

  • Lipid A and the core region
  • Polysaccharide chains

Now, the polysaccharide chains will be connected to the lipid A core region association by ligases, and with the aid of transport pores (Bayer 's junctions) in the outer membrane. This process is passive and therefore possible without energy.

Reactions of the human body on endotoxic lipopolysaccharide effective

Get lipopolysaccharides in the blood, they bind there to the serum protein lipopolysaccharide -binding protein ( LBP or septin called ). This complex binds to the membrane receptor CD14, inter alia, on the Monozytenoberfläche and NF-KB induced by the release of tumor necrosis factor and interleukin- 1β by these CD14 -bearing cell. The CD14 expression is again temporarily paracrine TNF induced (positive self-reinforcement ).

Lipopolysaccharide can enter directly into the brain and its own receptor, CD14, induce increased starting from there, especially in the microglia, and then locally to stimulate the subsequent cytokine production by circumventricular organs ( bodies with a permeable blood -brain barrier ). This is one of the ways that lead to fever.

Destruction of lipopolysaccharides

Heat-resistant devices can be obtained by heating for 5 hours at 200 ° C. rid of the lipopolysaccharides and non-heat -resistant equipment with 1 molar sodium hydroxide solution, which is to stand for 15 hours.

Rhamnose Kauffman–White classification Widal test Hydrophile Polymerase Paracrine signalling
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