Wikipedista:Adam je chemik/Pískoviště
Šablona:Short description
Šablona:Distinguish
Šablona:Enzyme
Chymosin Šablona:IPAc-en or rennin Šablona:IPAc-en is a protease found in rennet. It is an aspartic endopeptidase belonging to MEROPS A1 family. It is produced by newborn ruminant animals in the lining of the abomasum to curdle the milk they ingest, allowing a longer residence in the bowels and better absorption. It is widely used in the production of cheese. Bovine chymosin is now produced recombinantly in Šablona:Nobr, Aspergillus niger var awamori, and Šablona:Nobr as alternative resource.
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Charge interactions between histidines on the kappa-casein and glutamates and aspartates of chymosin initiate enzyme binding to the substrate.[1] When chymosin is not binding substrate, a beta-hairpin, sometimes referred to as "the flap," can hydrogen bond with the active site, therefore covering it and not allowing further binding of substrate.[2]
Examples
editovatListed below are the ruminant Cym gene and corresponding human pseudogene:
| Šablona:Infobox nonhuman protein | Šablona:Infobox protein |
FPC was the first artificially produced enzyme to be registered and allowed by the US Food and Drug Administration. In 1999, about 60% of US hard cheese was made with FPC[3] and it has up to 80% of the global market share for rennet.[4]
By 2008, approximately 80% to 90% of commercially made cheeses in the US and Britain were made using FPC.[5] The most widely used fermentation-produced chymosin is produced either using the fungus Aspergillus niger or using Kluyveromyces lactis.
FPC contains only chymosin B,[6] achieving a higher degree of purity compared with animal rennet. FPC can deliver several benefits to the cheese producer compared with animal or microbial rennet, such as higher production yield, better curd texture and reduced bitterness.[7]
References
editovat- ↑ Chybná citace: Chyba v tagu
<ref>; citaci označenéGillilandnení určen žádný text - ↑ Chybná citace: Chyba v tagu
<ref>; citaci označenépmid9862200není určen žádný text - ↑ Food Biotechnology in the United States: Science, Regulation, and Issues [online]. U.S. Department of State [cit. 2006-08-14]. Dostupné online.
- ↑ Johnson ME, Lucey JA. Major technological advances and trends in cheese. Journal of Dairy Science. April 2006, s. 1174–8. doi:10.3168/jds.S0022-0302(06)72186-5. PMID 16537950.
- ↑ Chymosin [online]. GMO Compass [cit. 2011-03-03]. Dostupné v archivu pořízeném z originálu dne 2015-03-26.
- ↑ Bovine chymosins A and B differ by one amino acid residue. This is probably an alleic variant, according to Uniprot:P00794. The two isoforms have identical catalytic activity, so any improvement in the product is due to the elimination of other impurities.
- ↑ Chybná citace: Chyba v tagu
<ref>; citaci označenéLaw 2010 100–101není určen žádný text
Further reading
editovat- Foltmann B. A review on prorennin and rennin. Comptes-Rendus des Travaux du Laboratoire Carlsberg. 1966, s. 143–231. PMID 5330666.
- Visser S, Slangen CJ, van Rooijen PJ. Peptide substrates for chymosin (rennin). Interaction sites in kappa-casein-related sequences located outside the (103-108)-hexapeptide region that fits into the enzyme's active-site cleft. The Biochemical Journal. June 1987, s. 553–8. doi:10.1042/bj2440553. PMID 3128264.
External links
editovatŠablona:Aspartic acid proteases
Šablona:Enzymes
Šablona:Portal bar
[[Category:EC 3.4.23]]
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Fyzikální vlastnosti
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Barnardova hvězda – červený trpaslík spektrální třídy M4 – svítí příliš slabě na to, aby ji bylo možné pozorovat bez dalekohledu. Má zdánlivou hvězdnou velikost 9,54 mag,kdežto nejjasnější hvězda oblohy, Sirius a nejslabší hvězda pozorovatelná pouhým okem 6 mag; proto magnituda 9,54 je pouze 1/27 jasnosti nejslabší hvězdy pozorovatelné pouhým okem za dobrých světelných podmínek.[2]
