Name: how cells control product buildup
Uploaded: 2019-03-11T09:21:10.000Z
Duration: 46 s
Channel: JoVE

In einem regulatorischen Prozess, der Feedback-Hemmung bezeichnet wird, hemmt das Produkt einer Reaktion ein Enzym in einem früheren Stadium des Stoffwechselwegs, der es produziert, wodurch die eigene Produktion verlangsamt oder gestoppt wird.
 Das Produkt bewirkt das, indem es sich an die regulatorische Stelle auf dem Enzym bindet, die sich von der aktiven Stelle unterscheidet, die an das Substrat bindet.
 Wenn sich das Produkt an die regulatorische Stelle bindet, verursacht es eine Konformationsänderung des Enzyms, die es daran hindert, die Reaktion weiter zu katalysieren.
 Diese Aktivität verhindert, dass sich zu hohe Mengen des Produkts ansammeln.
 Sobald die Menge niedrig genug ist, hemmt das Produkt das Enzym nicht mehr und die Produktion kann wie gewohnt fortgesetzt werden.

Sander, Timur, Niklas Farke, Christoph Diehl, Michelle Kuntz, Timo Glatter und Hannes Link. "Allosteric feedback inhibition enables robust amino acid biosynthesis in e. coli by enforcing enzyme overundance." Cell Systems 8, no. 1 (23. Januar 2019): 66-75.e8. [<a href="https://doi.org/10.1016/j.cels.2018.12.005" target="__blank">Quelle</a>]

Bulfer, Stacie L., Erin M. Scott, Lorraine Pillus und Raymond C. Trievel. "Strukturelle Grundlage für die Hemmung der L-Lysin-Rückkopplung der Homocitratsynthase." Das Journal of Biological Chemistry 285, Nr. 14 (2. April 2010): 10446–53. [<a href="https://doi.org/10.1074/jbc.M109.094383" target="__blank">Quelle</a>]

endprodukt-hemmung

Feedback Inhibition

Biochemische Reaktionen laufen in Zellen ständig ab und wandeln Substrate in verschiedene Produkte um. Dies geschieht in der Regel mit Hilfe von Enzymen, welche die Reaktionen beschleunigen. Ohne Enzyme würden die meisten Reaktionen innerhalb der Zelle viel zu lange dauern um nützlich für die Zelle zu sein.
 
 Da Enzyme helfen, die Reaktionsgeschwindigkeit zu kontrollieren, wird ihre Aktivität stetig reguliert, so dass angemessene Mengen an Substraten, Zwischenprodukten und Produkten in der Zelle erhalten bleiben. Ein übermäßiger Auf -oder Abbau von Substanzen kann katastrophale Folgen für die Gesundheit einer Zelle und des Organismus haben.
 
 In einem regulierten Prozess, der Endprodukt-Hemmung, inhibiert das Produkt ein Enzym, in einem früheren Schritt der Reaktionskette in dem es produziert wurde. Das Produkt bindet an die regulatorische Bindungsstelle des Enzyms. Sie unterscheidet sich von dem aktiven Zentrum, an dem das Substrat bindet. Dadurch wird die eigene Produktion verlangsamt oder vollständig unterbunden. Wenn das Produkt an die regulatorische Bindungsstelle bindet, verursacht es eine Konformationsänderung im Enzym. Diese verhindert, dass es an das Substrat binden kann und die Reaktion weiter katalysiert.
 
 Das verhindert, dass sich zu hohe Produktmengen in der Zelle ansammeln. Sinkt der Wert des Produkts ausreichend ab, hemmt es das Enzym nicht mehr. Die Reaktion kann wieder normal ablaufen.

Endprodukt-Hemmung

In den Zellen finden ständig biochemische Reaktionen statt, die Ausgangsstoffe in verschiedene Produkte umwandeln, meist mit Hilfe von Enzymen, die die ...

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how cells control product buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products.

If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important control process is feedback inhibition. In this process, the final product of a reaction slows an enzyme from an earlier step in the same pathway.

The product binds to a regulatory site on the enzyme. This site is different from the active site, which is where the substrate normally binds. Binding at the regulatory site changes the enzyme’s shape. That conformational change prevents the enzyme from binding the substrate and keeps the reaction from continuing.

Feedback inhibition helps stop too much product from accumulating in the cell. When product levels fall, the product no longer inhibits the enzyme. The pathway can then start again and continue producing the molecule as needed.

How Cells Control Product Buildup

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Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

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feedback inhibition

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

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key terms and concepts

Learn how feedback inhibition lets cells regulate enzymes, stop product buildup, and keep metabolic reactions balanced in high school biology.

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How Cells Control Product Buildup

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