factors affecting enzyme activity

temperature the rise in temperature makes the enzyme molecules vibrate more the increase in kinetic energy means more collisions occur with a higher energy, which means more reactions are likely to happen if the vibrations get too much, the bonds of the tertiary structure of the protein will break and the active site will change shape and the enzyme and substrate no longer fit together. this is called denaturing pH all enzymes have an optimum pH value.most work best at pH 7. pepsin works best at pH 2, which is useful because it is found in the stomach at a low pH (acidic) the increased concentrations of h+ ions interfere with the i9onic and hydrogen bonds in the tertiary structure, which cause it to denature. this is the same at high pH (alkali) because there is increase oh- ions which also interfere with the bonds enzyme concentration the more enzyme molecules there are in a solution, the more likely a substrate is to collide with one to form an enzyme-substrate complex if the amount of substrate is limited, there comes a point where there is too much enzyme for the amount of substrate and so the rate will plateau the substrate concentration is now the limiting factor substrate concentration the higher the substrate concentration, the faster the reaction- more substrate molecules means a collision between a substrate and an enzyme is more likely and so more sites will be used this is true until the 'saturation' point, where the concentration of enzyme becomes the limiting factor substrate concentration decreases over time as reactions occur, so if no variables are changes, the rate of reaction will decrease over time too. this makes the initial rate of reaction, the highest rate of reaction