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19 Cards in this Set

  • Front
  • Back

How is enzyme activity regulated?

By cofactors that activate enzymes and inhibitor molecules that stop or slow down the RoR

How does a competitive inhibitor work and what is its effect of RoR and Vmax?

It has a similar shape to the substrate and competes and temporarily binds to the active site preventing the substrate from entering so the enzyme is inhibited



It lowers RoR but Vmax can still be achieved if substrate conc. increases

What are the two examples of competitive inhibitors?

Statins are inhibitors of an enzyme used in the synthesis of cholesterol



Aspirin irreversibly inhibits the active site of COX enzymes preventing the synthesis of chemicals responsible for pain and fevers

How do non-competitive inhibitors work?

Inhibitor binds to enzyme at the allosteric site, this binding causes the tertiary structure to change thus changing the active site shape



It doesn't compete with the substrate and the enzyme no longer has a complementary set shape to the substrate and is inhibited

How do non competitive inhibitors affect Vmax?

It lowers and slows the rate of Vmax

What are two examples of non-competitive inhibitors?

Organophosphates used in herbicides and pesticides irreversibly inhibit an enzyme necessary for nerve impulse transmission



Cyanide ions, a metabolic poison, inhibits an enzyme used in ATP production so no energy can be released within a cell

What are end-product inhibitors and how do they work?

Products of a reaction act as inhibitor to the enzyme that produced it and regulates the RoR

What are cofactors?

Non-protein components necessary for the effective functioning of an enzyme

What are the subgroups of cofactors?

Inorganic cofactors


Coenzymes


Prosthetic groups

What are inorganic cofactors responsible for, how are they obtained and give an example...

Responsible for the transfer of atoms between reactions



Obtained through a diet as minerals



Amylase contains a chloride ion that is necessary for the formation of a correctly shaped active site


(Chloride kills organic things so it is inorganic)

What are prosthetic groups and give an example

A type of cofactor and is a permanent part of the enzyme



Zn 2+ ions form part of the structure in carbonic anhydrase an enzyme necessary for the metabolism of CO2

What are coenzymes and how are they obtained?

They are organic cofactors that are held loosely to the enzyme



They are derived from vitamins (organic molecules)

Give two examples of coenzymes...

Vitamin B3 is used to synthesise NAD a coenzyme responsible for the transfer of H atoms between molecules in respiration



Vitamin B5 is used to make coenzyme A which is essential for the breakdown of fatty acids and carbs in respiration

What are precursor enzymes?

Inactive enzymes that need to undergo a change in tertiary structure (active site) in order to be activated


They may cause damage in the cell or tissue where they're produced

What is the name for an inactive and activated enzyme?

Apoenzyme and holoenzyme

How can the tertiary structure of a precursor enzyme be changed?

The addition of a cofactor to the active site



The action of another enzyme that breaks bonds



A change in conditions (pH or temperature)

What is a zymogen or proenzyme?

An inactive enzyme that has proteins blocking the active site, cleaving this peptide activates the enzyme



(There was a pro called zymo that loved chopping meat)

What is an example of a proenzyme or zymogen?

Pepsinogen is released into the stomach where the tertiary structure changes shape due to low pH

What would the curve for competitive and noncompetitive inhibitors look like on a graph?