the effect of pH on the rate of enzyme activity

• enzyme - catalase is an enzyme found in a wide variety of living things like liver celery and potatoes
• substrate - hydrogen peroxide
• produces - water and oxygen (producing foam)
• safety - hydrogen peroxide is an irritant. safety googles, lab coat and gloves should be worn
• 1 - put some pH buffer 4 into a graduated cylinder
• 2 - add one drop of washing up liquid to the graduated cylinder - when oxygen meets the washing up liquid a froth will be seen. Only one drop is added otherwise too mush foam would be produced too quickly
• 3 - chop and blend a celery stalk for 3 seconds (contain catalase) and add some water
• 4- filter the solution using coffee filter paper and add some filtrate to the graduated cylinder (the filtrate contains the enzyme catalase)
• 5 - put 10cm cubed of hydrogen peroxide into a test tube and stand in a water bath
• 6 - place the graduated cylinder into the same water bath at 25 degrees for 5 minutes (this allows all the regents to be at the same temperature)
• 7 - pour the hydrogen peroxide into the graduated cylinder
• 8 - after 2 minutes record the volume at the top of the froth
• 9 - repeat steps 1 to 8 using different pH buffers
• 10 - As a control, use the same materials but leave out the celery (no enzyme). the result in this case is that no froth is produced