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Factors affecting enzyme activity - Coggle Diagram
Factors affecting enzyme activity
Inhibitors
Non-competitive inhibitor
They are molecules that bind to the enzyme but far away from the active site.
This causes the active site to change shape so the substrate can no longer bind to it.
They don't 'compete' with the substrate they are just there.
Increasing the concentration of the substrate therefore won't make any difference.
Competitive inhibitor
High concentration of the inhibitor will take up lots of the active sites.
Higher concentration of substrate means it should reach the active site first.
It can depend on the concentrations of both the substrate, enzyme and the inhibitor.
Instead they block the active site.
They bind to the active site but no reaction occurs.
They have a similar shape to the substrate.
Concentration
Enzyme concentration
But, if the amount of substrate is limited, there comes a point when there's more than enough enzyme molecules to deal with all the available substrate, so adding more enzyme has no further effect.
The more enzyme molecules there are in a solution, the more likely the substrate molecules will collide with one and form an enzyme-substrate complex.
Increase in enzyme = increase in rate of reaction
Substrate concentration
The higher the substrate concentration, the faster the reaction - more substrate molecules means a collision between substrate and enzyme is more likely and so more active sites will be used. This is only true up until a 'saturation' point though. After that, there are so many substrate molecules that the enzymes have about as much as they can cope with (all the active sites are full), and adding more makes no difference.
Substrate concentration decreases with time during a reaction (unless more substrate is added to the reaction mixture), so if no other variables are changed, the rate of reaction will decrease over time too. This makes the initial rate of reaction (start rate) the highest rate of reaction.
pH
All enzymes have an optimum pH value. Most human enzymes work best at pH 7. However, certain ones work better in other environments like pepsin found in the stomach (pH 2). The H+ and OH- ions found in acids and alkalines can mess up the ionic bonds and hydrogen bonds.
Temperature