Factors That Affect the Rate of Reaction of Peroxidase

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Factors that Affect the Rate of Reaction of Peroxidase

Purpose:
To determine the effect of various factors on the rate of reaction between an enzyme and its substrate, and also to determine the optimal ranges under which the enzyme activity is maximized. Also to determine whether saline and alcohol are inhibitors or activators

Hypothesis:
PH factor prediction: I predict that as the pH increases so the activity of the enzyme will increase until it reaches optimum pH range (pH 7) because the enzyme is less denatured when it reaches the preferred pH level, and after this it will decrease because the active site will change in shape and it will no longer accept substrates.

Temperature factor prediction: I predict as the temperature increases, the enzyme activities will increase because there is more energy to speed up the reaction until it reaches the optimum temperature range (room temperature which is about 20 °C), and after that the enzyme activities will decrease because of denature of the enzymes (cause changes to active site that will no longer fit substrate)

Concentration of enzymes prediction: I predict that as the concentration of enzyme increases, so the enzyme activities will increase because there is more enzyme to react with the substrates however when enzymes get saturated, the reaction will come to a plateau because eventually all the substrates will have enzymes to react with, and any extra will have no effect on the reaction whatsoever.

I predict alcohol is an inhibitor of Peroxidase because alcohol when alcohol bind to the allosteric site it changes the active site shape of the enzymes thus deactivating enzymatic activities

I predict salt is an activator of Peroxidase because salt contains Na ions which attaches to the allosteric site changing the shape of the enzyme to fit a substrate.

Materials:
• Peroxidase (enzyme in potato)
• Hydrogen peroxide, 3%
• A strong acid, pH3 (lemon juice, or HCL) 0.5
• A strong base, pH 10 (drain cleaner, NaOH) 0.5 mol/L • A weak acid, pH 6 (vinegar, acetic acid( CH3COOH)) 0.5 mol/L • A weak base, pH 8 (baking soda, sodium bicarbonate (NaHCO3)) 0.5 mol/L a • A saline solution, pH 7 (table salt, NaCl) 0.5 mol/L • Alcohol, pH 7 (rubbing or spirits (isopropyl or ethanol)) 1 mol/L • Distilled water, pH 7

• Hot plate, stove, or kettle (hot water bath)
• Cold water (ice water bath)
• Eye dropper or oral, needle-less syringe 10 cc (10 mL) • Graduated cylinder or needle-less syringe 10 cc( 10 mL) • Disposable plastic plates
• Disposable plastic cups
• Thermometer
• Timing device (with second hand)
• ice

Safety Precautions

Being sure to wash hands before and after handling materials. Use caution with hot and cold materials. Follow all safety procedures.

Procedure:
• I placed a piece of raw potato in 10 mL of water at room temperature (20 °C) for three minutes. Put three drops of hydrogen peroxide (3 %) on it (after dabbing dry with paper towel)

• I placed a piece of raw potato in 10 mL of cold water at temperature 10 °C for three minutes. Put three drops of hydrogen peroxide (3 %) on it (after dabbing dry with paper towel) to observe the effect of temperature on reaction activity

• I placed a piece of raw potato in 10 mL of cold water at temperature 15 °C for three minutes. Put three drops of hydrogen peroxide (3 %) on it (after dabbing dry with paper towel) to observe the effect of temperature on reaction activity

• I placed a piece of raw potato in 10 mL of hot water at room temperature 25 °C for three minutes. Put three drops of hydrogen peroxide (3 %) on it (after dabbing dry with paper towel) to observe the effect of temperature on reaction activity

• I placed a piece of raw potato in 10 mL of hot water at temperature 30 °C for three minutes. Put three drops of hydrogen peroxide (3 %) on it (after dabbing dry with paper towel) to...
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