5.0 Enzymes Flashcards
Define enzyme
Biological catalysts made from proteins that controls specific chemical reactions, making life possible
Define catalyst
Substance that increases rate of reaction without being changed itself
How do enzymes work
Lower activation energy required for reaction
What is a substrate
The beginning molecule in the reaction that binds to enzymes forming an enzyme-substrate complex
What is an active site
A site on the enzyme highly specific for bindings of certain molecules
What is heme
An organic compound containing an iron atom between the structure of the porphyrin ring
Can an enzyme release products to perform other reactions
Yes
What is the fastest enzyme
Catalase
Are enzyme reactions reversible
Yes
Conditions that affect enzyme activity
- Amount of substrate
- Temperature
- pH
- ionic conditions
- presence of coenzyme/cofactor
- presence of inhibitors
- presence of heavy metals
- availability of energy
What is saturation in enzyme reactions
When all active sites of an enzyme are occupied
2 cofactors enzymes need to be able to work
- inorganic ions (eg. Zn, Fe,…)
- non-protein organic molecules
+ prosthetic groups (permanently bound) - heme in catalase
+ coenzymes: organic molecules that react with the substrate and released with the enzyme - ATP, NAD (vitamin B3)
Are enzymes specific in catalysing a reaction
Usually
Example of specific reaction of an enzyme
Invertase catalyses hydrolysis of sucrose to glucose and fructose only
What is irreversible inhibition
When a covalent bond is formed between the inhibitor and the enzyme, and isn’t easily broken - bad for us
What is reversible inhibition
The inhibitor molecule is bound by the enzyme through attractive forces - drugs, natural regulations of key enzymes in cells
2 types of reversible inhibition
- Competitive inhibitor: blocks substrate from entering active site
- Non-competitive inhibitor: doesn’t bind to active site but changes shape of enzyme so it doesn’t bind to substrate
Factors that affect enzyme activity
- Substrate concentration
- Increase in temperature
- change in pH
What is the optimum temperature for enzymes to react in our bodies
37
Why does the rate of reaction falls rapidly above certain temperatures
Enzymes are proteins - they denature above certain temepratures
What happens to a partially denatured enzyme
It regains its shape after cooling
What happens to a completely denatured enzyme
It can’t function correctly again
Why do chemical reactions require activation energy
- reactants must collide to react
- intermolecular forces must be overcome
- chemical bonds must be broken
What are the chemicals involved within a reaction
Reactants
