Essay On The Effect Of Temperature On Peroxidase

To determine the effects of two environmental factors, temperature and pH, on the enzyme peroxidase, a spectrophotometer was used to measure the absorbance of each reaction every twenty seconds for two minutes. The temperatures tested were 0°C, 23°C, 32°C, and 48°C; the pH levels tested were pH 3, pH 5, pH 7, and pH 9. The temperatures were kept constant by keeping the tubes at room temperature, or placing them in an ice bath, warmer, or a hot water bath. Peroxidase, hydrogen peroxide, guaiacol and a pH buffer were mixed together to produce a reaction for both the temperature and pH experiments. The optimum temperature for peroxidase activity, 23°C, was determined by taking the highest rate of absorbance of the four temperature reactions

The reaction for pH 5 went off scale at one hundred seconds; its reaction went faster than the other tested pH levels. At twenty seconds, the pH 9 reaction reached 0.244 absorbance, slowly increased, and then slightly dropped to 0.296 by the end of the reaction (Figure 3). The rate of absorbance for peroxidase with pH 9 was 0.0097, so peroxidase activity is least optimal at pH 9. The absorbance rate for pH 3 was 0.0866, and the rate for pH 7 was 0.1426. Because the rate of absorbance for pH 5 was 0.3493, it is the optimum pH level for peroxidase. Highly acidic and alkaline pH levels reduce activity. (Figure

Figure 3: The absorbance of peroxidase reactions over two minutes using pH 3, pH 5, pH 7, and pH 9. Figure 4: The rate of absorbance of peroxidase reactions at the tested pH levels.

Discussion This experiment was conducted to determine the effects of pH and temperature on peroxidase from a potato. The optimum temperature for peroxidase was determined to be 23°C, because it had a rate of absorbance of 0.3493, higher than the other temperatures evaluated. A temperature of 48°C is inefficient of speeding up peroxidase activity because its rate of absorbance was 0.001. Peroxidase activity’s optimum pH was found to be pH 5, since the absorbance rate was the highest at 0.3493. Little activity occurred at pH 3, but the absorbance of the reaction with pH 7 rose steadily to 0.99. The rate of absorbance for peroxidase with pH 9 was 0.0097; pH 9 is incapable of accelerating enzyme activity. This suggests that an alkaline pH is inferior to an acidic pH in increasing peroxidase activity, and that the higher the pH level, the poorer the pH boosts the reaction. A highly acidic pH also reduces