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Flashcards in Enzyme Deck (23):

Where does the substrate fit?

The substrate fits to the active site (aktives Zentrum) of the enzyme via the lock-and-key system. 


What is one of the properties of the substrate which binds to the enzyme besides the lock-and-key system?

Charges of the amino acid in the active site contribute in holding the substrate.


What type of proteins reduce the activation energy?



How does an enzyme catalyze  a reaction?

If the substrate molecule collides (DE: kollidieren) with the active siede (DE: aktives Zentrum) of the enzyme an enzyme-substrate complex is formed. 


What happens to a molecule if heat is added?

Molecules move faster, vibrate and bonds are broken.


What happens to an enzyme if more and more heat is added?

Weak bonds hold the tertiary structure of the enzyme. Those bonds are broken and enzyme stops working which is called denaturation (DE: Denaturierung).


What happens if the pH changes?

Large numbers of hydrogen and ionic bonds are responsible for holding the tertiary structure of an enzyme. If the pH changes the tertiary structure of the enzyme will change. 


Induced-fit hypothesis

The favored model for the enzyme-substrate interaction is the induced fit model.[1] This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding.



Cofaktor (DE)

Prosthetische Gruppe
Ein organisches Molekül, das kovalent an ein Enzym gebunden ist; die prosthetische Gruppe kann also nicht dissoziieren.

Ein niedermolekulares organisches Molekül, das nicht-kovalent an ein Enzym bindet und daher nach der Katalyse wieder dissoziiert. Es nimmt während der Reaktion chemische Gruppen, Protonen oder Elektronen auf oder gibt diese ab, wodurch sich seine Reaktivität verändert.[2] Ein Coenzym geht also – wie die prosthetische Gruppe – verändert aus der Reaktion hervor[3] und muss daher neu in den Ursprungszustand überführt werden, jedoch geschieht das meist nicht am Enzym.

Metall-Ionen, die an ein Enzym gebunden und für dessen Katalyse erforderlich sind, gehören ebenfalls zu den Cofaktoren. Das entsprechende Enzym wird Metalloenzym genannt.


What does the end product do after the enzyme controlled reaction?

The end product attaches itself to the enzyme which is in the early stage of the reaction and works as a non-competitive inhibitor.


What is a limiting factor of an enzyme?



Why are enzyme concentrations usually low in a cell?

Because enzyme being a catalyst work over and over again the same reaction.


Describe the 2 types of enzyme inhibition

Kompetitive Hemmung (Competitive inhibition)
kompetitive Hemmung (lat. competere, zusammen etwas begehren) wird in der Biochemie und Pharmakologie eine Enzymhemmung bezeichnet, bei der ein Agonist und ein Antagonist um die Besetzung eines Rezeptors konkurrieren, wobei der Antagonist keine biochemische Wirkung hat. Die entsprechenden antagonistischen Substanzen bezeichnet man als kompetitive Antagonisten.


Nichtkompetitiver Antagonist (Non-competitive inhibition)
Als nichtkompetitiver Antagonist wird in der Pharmakologie und Biochemie eine Substanz bezeichnet, die in der Lage ist, die Bindung eines Agonisten an einen Rezeptor zu hemmen, ohne dass diese Substanz durch den Agonisten verdrängt werden kann. Nichtkompetitive Antagonisten können an eine andere (allosterische) Bindungsstelle als der Agonist an den Rezeptor binden. 



What  happens if the concentration of the substrate increases in an enzyme-inhibition reaction?

Competitive inhibitiors
- level of inhibition decreases because a substrate molecule is more likely than an inhibitor molecule to collide with an active site
-competitive inhibitors just bind for a short period


non-competitive inhibitiors
-no effect
-they bind permanently so that the enzyme is denatured


Which enzyme breaks milk sugar, lactose into glucose and galactose monomers?


Lactose-intolerant individuals do not produce lactase and suffer stomach cramps, bloating and diarrhoea if they take in milk products.


What is the function of catalase (Katalase)?

The breakdown of hydrogen peroxide to water and oxygen gas. Almost all organisms produce catalase because hydrogen peroxide is a toxic by-product of some metabolic reactions.


What is the function of ribulose bisphosphate carboxylase (rubisco; DE: Rubisco)

Plants need carbon dioxide for photosynthesis. The enzyme rubisco catalyses the binding of carbon dioxide to a molecule called ribulose biphosphate.


What is the function of ATP-ase (DE: ATPase)?

The breakdown of ATP to produce ADP and a phosphate group. This reaction releases a small amount of energy that is used to drive energy requiring processes such as active transport.


What is the function of glycogen synthetase (DE: Glykogensynthetase)?

The building up of glycogen by catalysing the joining together of glucose molecules. Glycogen is the storage carbohydrate of animals.


What are the advantages of enzymes?

They are specific to one catalytic reaction and do not produce a range of unwanted by-products.


Why are enzymes proteins?

Only proteins can produce such a wide variety of shapes. This is because proteins are made from 20 different amino acid sub-units.


Describe 2 type of enzymes

Extracellular (extrazellulaer )enzymes which catalyse reactions outside the cell 

Intracellular enzymes which catalyse ractions inside the cell


How are large molecules broken down in the digestive system?

Large molecules are broken down by breaking the glycosidic-, peptide- and ester bonds through enzymes.

glycosidic bond= DE: Glycosidbindung