酵素活性

Mix equal volumes of 0.1 M sodium phosphate monobasic and 0.1 M sodium phosphate dibasic solutions to achieve a final volume of 500 mL. Test the resulting solution using a pH meter to ensure it falls between pH 6.8 and 7.2. This buffer maintains optimal enzyme stability during extraction and storage.

Remove the outer layer of a turnip and cut it into approximately two cm cubes. Place 30 g of turnip cubes into a blender with 300 mL extraction buffer, and blend at high speed three times for about 15 seconds each. Filter the homogenized mixture through three layers of cheesecloth, then strain through one coffee filter and refrigerate immediately.

Add 15 mL of 3% hydrogen peroxide to 435 mL distilled water to dilute the H2O2 to a 0.1% concentration. This diluted substrate solution is used to measure enzyme activity by providing the substrate that the enzyme catalyzes, producing measurable color changes.

Guaiacol serves as a color-changing reactant that indicates enzyme activity. Dissolve 0.2 mL concentrated guaiacol in 100 mL of isopropyl rubbing alcohol and store in the refrigerator. When peroxidase catalyzes the reaction with hydrogen peroxide, guaiacol undergoes oxidation, producing a visible color change that allows quantification of enzyme performance.

Multiple pH buffers allow investigation of how pH affects peroxidase activity. Add 100 mL distilled water to six 250 mL beakers and add buffer capsule contents with pH values of 3, 4, 5, 6, 7, and 8 to separate beakers. Testing enzyme activity across this pH range reveals the optimal pH for peroxidase function and demonstrates enzyme sensitivity to environmental conditions.

The filtrate containing extracted peroxidase must be immediately placed in a refrigerator after preparation. Cold storage preserves enzyme structure and catalytic activity by slowing degradation and denaturation. Proper storage ensures consistent and reliable enzyme activity measurements throughout the experiment and maintains data integrity.

The diluted 0.1% hydrogen peroxide substrate provides a consistent reaction medium for measuring enzyme kinetics and performance. Standardized substrate concentration ensures that observed activity changes reflect true differences in enzyme function under varying pH and temperature conditions rather than substrate availability limitations.