Enzyme Notes
Enzymes
All enzymes are globular proteins and round in shape
They have the suffix "-ase"
Intracellular enzymes are found inside the cell
Extracellular enzymes act outside the cell (e.g. digestive enzymes)
Enzymes are catalysts → speed up chemical reactions
Reduce activation energy required to start a reaction between molecules
Substrates (reactants) are converted into products
Reaction may not take place in absence of enzymes (each enzyme has a specific catalytic action)
Enzymes catalyse a reaction at max. rate at an optimum state
Induced fit theory
Enzyme's shape changes when substrate binds to active site
Amino acids are moulded into a precise form to perform catalytic reaction effectively
Enzyme wraps around substrate to distort it
Forms an enzyme-substrate complex → fast reaction
E + S → ES → P + E
Enzyme is not used up in the reaction (unlike substrates)
Changes in pH
Affect attraction between substrate and enzyme and therefore efficiency of conversion process
Ionic bonds can break and change shape / enzyme is denatured
Charges on amino acids can change, ES complex cannot form
Optimum pH pH 7 for intracellular enzymes
Acidic range (pH 1-6) in the stomach for digestive enzymes (pepsin)
Alkaline range (pH 8-14) in oral cavities (amylase)
Increased Temperature
Increases speed of molecular movement → chances of molecular collisions → more ES complexes
Enzymes have optimum temp. for their action (varies between different enzymes)
Above ≈42°C, enzyme is denatured due to heavy vibration that break
Shape is changed / active site can't be used anymore
Decreased Temperature
Enzymes become less and less active, due to reductions in speed of molecular movement
Below freezing point
Inactivated, not denatured
Regain their function when returning to normal temperature
Inhibitors
Slow down rate of reaction of enzyme when necessary (e.g. when temp is too high)
Molecule present in highest conc. is most likely to form an ES-complex
All enzymes are globular proteins and round in shape
They have the suffix "-ase"
Intracellular enzymes are found inside the cell
Extracellular enzymes act outside the cell (e.g. digestive enzymes)
Enzymes are catalysts → speed up chemical reactions
Reduce activation energy required to start a reaction between molecules
Substrates (reactants) are converted into products
Reaction may not take place in absence of enzymes (each enzyme has a specific catalytic action)
Enzymes catalyse a reaction at max. rate at an optimum state
Induced fit theory
Enzyme's shape changes when substrate binds to active site
Amino acids are moulded into a precise form to perform catalytic reaction effectively
Enzyme wraps around substrate to distort it
Forms an enzyme-substrate complex → fast reaction
E + S → ES → P + E
Enzyme is not used up in the reaction (unlike substrates)
Changes in pH
Affect attraction between substrate and enzyme and therefore efficiency of conversion process
Ionic bonds can break and change shape / enzyme is denatured
Charges on amino acids can change, ES complex cannot form
Optimum pH pH 7 for intracellular enzymes
Acidic range (pH 1-6) in the stomach for digestive enzymes (pepsin)
Alkaline range (pH 8-14) in oral cavities (amylase)
Increased Temperature
Increases speed of molecular movement → chances of molecular collisions → more ES complexes
Enzymes have optimum temp. for their action (varies between different enzymes)
Above ≈42°C, enzyme is denatured due to heavy vibration that break
Shape is changed / active site can't be used anymore
Decreased Temperature
Enzymes become less and less active, due to reductions in speed of molecular movement
Below freezing point
Inactivated, not denatured
Regain their function when returning to normal temperature
Inhibitors
Slow down rate of reaction of enzyme when necessary (e.g. when temp is too high)
Molecule present in highest conc. is most likely to form an ES-complex