Avidin

Avidin is a glycoprotein of avian eggs in the protein capable of binding biotin (vitamin H). The biological function of avidin is not known in detail. However, it is believed that the protein is avidin in a defense mechanism, and an inhibitory effect on bacterial growth. In the egg, it makes up about 0.05 percent of the egg white protein.

Is a tetrameric protein, which may bind four biotin molecules. The ability of avidin to bind biotin, leading among other things to the fact that biotin can not be absorbed in the gastrointestinal tract when you eat lots of raw egg. Avidin reduces both the availability of the feed with the food as well as of the biotin produced by the intestinal flora. This can be produced experimentally by the addition of avidin or raw egg white to the normal diet, biotin deficiency.

Structure

The primary structure of the monomer, so each of the four identical subunits of 128 amino acids, the tetramer has a total molecular weight of 66 kDa.

Homologues

Streptavidin is a bacterial avidin from Streptomyces, which also binds biotin, albeit slightly weaker than the avidin. However, because the bacterial streptavidin and therefore it is not a glycoprotein, has lower non-specific binding, it is preferably used in biochemistry.

Discovery

1940, had observed that chicks that received a raw egg white, suffering from biotin deficiency. In the same year succeeded Esmond Emerson Snell as the first to isolate the corresponding protein. He named it after the avidin property of " greedy" (English " Avid " ) to connect with biotin.

Green Biotechnology

With the avidin- corn Transgenic corn was developed on a plant genetic engineering which is capable of expressing avidin in concentrations above 100 ppm. This protects the corn due to the binding of biotin especially during storage against insect infestation since it prevents the harmful insects can record it. In this way, crop losses are to be reduced by insect infestation during storage, especially in tropical countries. In addition, experiments were carried out as synergy effects of Bt maize and Avin can be used as an insect repellent.

Transgenic corn must be cooked for use as food and feed, as it is uncooked unusable for humans and other animals.

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