Aminopeptidases

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Aminopeptidases are enzymes that catalyze the cleavage of individual amino acids from the N -terminal end of a protein . Aminopeptidases are found in all living things. About 20 of them have been discovered in humans to date. In addition to protein maturation, they also serve to regulate peptide hormone levels and the digestion of proteins in the intestine in the human metabolism .

For example, a tetrapeptide ( Val - Gly - Ser - Ala ) with green -labeled N-terminal peptide-bound α-amino acid (in the example: L -valine ) is in the presence of a valine-specific aminopeptidases hydrolyzed , L -valine is the N -terminal Split off the end of the peptide. The tripeptide Gly – Ser – Ala remains.

Aminopeptidases belong to the group of exopeptidases , i. H. the protein-splitting enzymes , which split proteins at terminal peptide bonds. In most cases aminopeptidases belong to the metalloproteases . For all natural amino acids there are specific aminopeptidases which only split them off at the N -terminal end of a protein ( arginine aminopeptidase , leucine aminopeptidase , etc.). Many of these enzymes are tightly bound to the cell wall.

Catalyzed reactions

Peptidases break down proteins by hydrolyzing the peptide bonds . While endopeptidases break down proteins within their molecules, exopeptidases break them down from the “edge of the molecule”. Aminopeptidases specifically attack the N-terminal or amino-terminal end of the peptides and cleave off a single amino acid (such as aminoacyl peptide hydrolases and iminoacyl peptide hydrolases ).

Industrial application

Aminopeptidase can be used in the enzymatic, kinetic resolution of DL -2-arylglycine amides. When using an L -aminopeptidase as a catalyst, the L -2-arylglycine amide is hydrolyzed enantioselectively to L -2-arylglycine, while D -2-arylglycine amide remains unchanged.

Individual evidence

  1. H. Weber: Microbiology of Food. Milk and milk products , 1996, Behr's Verlag, ISBN 386022235X .
  2. Wissenschaft-Online-Lexika: Entry on amine peptidases in the Lexicon of Biochemistry ( Memento of the original from December 3, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.wissenschaft-online.de
  3. ^ RA Sheldon: The Industrial Synthesis of Optically Active Compounds , in Miklós Simonyi (editor), Problems and Wonders if Chiral Molecules , Akadémiai Kiadó, Budapest, 1990, pp. 349-386, ISBN 9630558815 .