Neuraminidase
| Neuraminidase | ||
|---|---|---|
| Properties of human protein | ||
| Secondary to quaternary structure | Tetramer | |
| Identifier | ||
| Gene names | NEW1 , NEW2, NEW3 | |
| Enzyme classification | ||
| EC, category | 3.2.1.18 , glycosidase | |
| Response type | hydrolytic cleavage | |
| Substrate | terminal sialic acid residues in oligosaccharides, glycoproteins, glycolipids, colominic acid and synthetic substrates | |
Neuraminidases ( sialidases ) are a family of enzymes that split sialic acids from amino - glycoproteins and thus make them digestible. Such enzymes are often found in viruses , bacteria , other unicellular organisms and parasites and fungi, but they also occur in the lysosomes and cell membranes of animals and humans. Here they are indispensable for the breakdown of the corresponding aminoglycoproteins and membrane gangliosides . A deficiency disease leads to increased levels of these substances in the blood and urine ( sialidosis ).
Viral enzyme
Neuraminidases are firmly anchored in the membrane of many ortho- and paramyxoviruses mumps , influenza types A and B and others. They cleave glycoproteins of the membranes of virus host cells and viruses themselves in order to free themselves from the infected cell after replication.
So-called neuraminidase inhibitors are drugs that slow down this process of cleavage from the host cell after an infection with influenza viruses. There are nine types of influenza A neuraminidase , labeled N1-9. The common designation combination H x N y (e.g. H 5 N 1 ) results in combination with another surface protein, the so-called hemagglutinin , and denotes the proteins present on the surface of the viruses that are essential for penetrating the host cell are necessary.
Endosialidase
An endosialidase has been identified in bacteriophages of the K1 family. In contrast to classic sialidases from, for example, influenza viruses, an endosialidase (endoN) does not cleave terminal sialic acid residues of glycoconjugates, but only inside sialic acid homo-oligomers and homo-polymers ( polySia ).
The crystal structure of an endosialidase was determined back in 2005.
Bacteria and parasites
Several indications that sialidases are important for the ingestion of many types of bacteria, especially intestinal bacteria , and the fact that many pathogenic germs have sialidase activity, show that the enzyme also plays an important role in the metabolism of bacteria. The same relationship between sialidase activity and pathogenicity was found in the causative agent of Chagas disease ( Trypanosoma cruzi ).
classification
Sialidases form the family 33 in the classification of glycosidases according to Henrissat.
literature
- E. Bonten, A. van der Spoel and a .: Characterization of human lysosomal neuraminidase defines the molecular basis of the metabolic storage disorder sialidosis. In: Genes & development. Volume 10, Number 24, December 1996, pp. 3156-3169, ISSN 0890-9369 . PMID 8985184 .
Individual evidence
- ^ A b Abraham Rosenberg: Biology of the Sialic Acids. Springer, 1995. pp. 261ff ISBN 0-306-44974-9
- ↑ RCSB Protein Data Bank: 1V0E Structure Summary , accessed April 3, 2020.
- ↑ Bernard Henrissat / UniProt: Glycosyl hydrolase families: classification and list of entries , accessed on April 3, 2020.
Web links
- Bernhard Peter: Neuraminidase depicted with molecular modeling
- Bernhard Peter: Neuraminidase with sialic acid, representations with molecular modeling
- David Goodsell: Molecule of the Month: Neuraminidase doi : 10.2210 / rcsb_pdb / mom_2009_5