Sandbox 300: Difference between revisions

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The protein A permit the inhibition of the phagocytosis, the process of vesicular internalization of solid particles, because of the interaction with mammal antibodies.

In a normal case of phagocytosis, the bacterium is eliminated during intracellular digestion, thanks to hydrolytic enzymes of phagocyte. At first, the particle is recognized and sticks on the phagocyte. The recognition is possible thanks to phagocyte membrane receptors, which recognize the Fc domain of immunoglobulins. Then the bacteria enter into the phagocyte by a process of endocytosis. The intracellular digestion takes place, and the bacterium is degraded by enzymes. To finish, cell fragments are removed by exocytosis.

In the case of S.aureus, in the serum, the interaction between Fc domain and protein A leads to the attachment in a wrong direction of the IgG to the bacterium: then, the recognition is not allowed and the cascade of reactions necessary for phagocytosis does not occur. By stopping this process and through other virulence factors, bacterial colonization is allowed, through the growth and dissemination of bacteria into the organism.

In the case of S.aureus, in the serum, the interaction between Fc domain and protein A leads to the attachment in a wrong direction of the IgG to the bacterium: then, the recognition is not allowed and the cascade of reactions necessary for phagocytosis does not occur. By stopping this process and through other virulence factors, bacterial colonization is allowed, through the growth and dissemination of bacteria into the organism<ref>http://en.wikipedia.org/wiki/Protein_A?oldid=252478781</ref>.

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==Protein A in laboratories==

===Application in methods of detection===

===Application in purification of antibodies===

Thanks to its properties with immunoglobulins, protein A is used in research in technics of purification of antibodies; this kind of purification is called “Class-specific Affinity”.

To accomplish the purification of IgG, the IgG-binding protein is immobilized onto a solid supports, like porous resins (for example, beaded agarose) or magnetic beads. This protein is often used, because it has an advantage: there are not orientation problems thanks to the 5 binding domains of the protein A with IgG. But this protein is relatively specific to IgG; for example, it binds very poorly or not at all IgM. To bind other antibody targets, we must use other proteins, such as protein L or G, which have different binding properties.

Then, the antibodies which are purified can be used to probe the specific antigen in Western blotting, ELISA (enzyme-linked immunosorbent assay) or other applications<ref>http://www.piercenet.com/browse.cfm?fldID=4E032172-5056-8A76-4EAE-8D395D2DCDA3</ref>.

==References==

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@@ Line 33: / Line 33: @@
 The protein A permit the inhibition of the phagocytosis, the process of vesicular internalization of solid particles, because of the interaction with mammal antibodies.
 In a normal case of phagocytosis, the bacterium is eliminated during intracellular digestion, thanks to hydrolytic enzymes of phagocyte. At first, the particle is recognized and sticks on the phagocyte. The recognition is possible thanks to phagocyte membrane receptors, which recognize the Fc domain of immunoglobulins. Then the bacteria enter into the phagocyte by a process of endocytosis. The intracellular digestion takes place, and the bacterium is degraded by enzymes. To finish, cell fragments are removed by exocytosis.
-In the case of S.aureus, in the serum, the interaction between Fc domain and protein A leads to the attachment in a wrong direction of the IgG to the bacterium: then, the recognition is not allowed and the cascade of reactions necessary for phagocytosis does not occur. By stopping this process and through other virulence factors, bacterial colonization is allowed, through the growth and dissemination of bacteria into the organism.
+In the case of S.aureus, in the serum, the interaction between Fc domain and protein A leads to the attachment in a wrong direction of the IgG to the bacterium: then, the recognition is not allowed and the cascade of reactions necessary for phagocytosis does not occur. By stopping this process and through other virulence factors, bacterial colonization is allowed, through the growth and dissemination of bacteria into the organism<ref>http://en.wikipedia.org/wiki/Protein_A?oldid=252478781</ref>.
@@ Line 40: / Line 40: @@
 ==Protein A in laboratories==
 ===Application in methods of detection===
+===Application in purification of antibodies===
+Thanks to its properties with immunoglobulins, protein A is used in research in technics of purification of antibodies; this kind of purification is called “Class-specific Affinity”.
+To accomplish the purification of IgG, the IgG-binding protein is immobilized onto a solid supports, like porous resins (for example, beaded agarose) or magnetic beads. This protein is often used, because it has an advantage: there are not orientation problems thanks to the 5 binding domains of the protein A with IgG. But this protein is relatively specific to IgG; for example, it binds very poorly or not at all IgM. To bind other antibody targets, we must use other proteins, such as protein L or G, which have different binding properties.
+Then, the antibodies which are purified can be used to probe the specific antigen in Western blotting, ELISA (enzyme-linked immunosorbent assay) or other applications<ref>http://www.piercenet.com/browse.cfm?fldID=4E032172-5056-8A76-4EAE-8D395D2DCDA3</ref>.
 ==References==
 <references/>