Cofactors 2.4.2 Flashcards
What are cofactors?
Cofactors are used if an enzyme can only work if another small non-protein molecule is attached to them.
When are cofactors often involved?
In catalysing oxidation-reduction reactions
What is a prosthetic group?
A cofactor that is permanently bound, by covalent bonds, to an enzyme molecule.
What is carbonic anhydrase?
An enzyme that contains a zinc ion permanently bound to its active site - which catalyses the interconversion on carbon dioxide and water to carbonic acid in RBC’s
- Enabling CO2 to be carried to the lungs
Give another example of a cofactor enzyme
Amylase, it only functions if chloride ions are present
What is a co-substrate?
Where the cofactor and substrate together form the correct shape for the active site.
State another way in which a cofactor can work
Some may use ions (cofactors) to ease the formation of the enzyme-substrate complex, therefore increasing the rate of reaction
What are co-enzymes?
Small non-protein molecules that temporarily bind to the active site - either just before or at the same time as the substrate
How do coenzymes change throughout a reaction?
They are chemically changed, and need to be returned to their original state - often by a different enzyme.
Where are many coenzymes derived from?
Water-soluble vitamins, hence why deficiency diseases occur as enzymes cannot function properly.
What coenzyme is derived from B12, and what disease is caused by its absence
Cobalamin coenzymes, disease - pernicious (progressive) anaemia
What coenzyme is derived from Nicotinamide (B3) and what disease is caused by its absence
NAD and NADP, disease = causes pellagra (diarrhoea, dermatitis and dementia)
