There is a certain temperature at which an enzyme's catalytic activity is at its greatest (see graph). This optimal temperature is usually around human body temperature (37.5 oC) for the enzymes in human cells.
Enzyme activity is said to be maximum in the pH between 5 and 7. Some enzymes, on the other hand, prefer a more drastic pH having an optimum pH of 1.7 to 2. In some other cases, the pH optima depends on where it is found. The optimum temperature of enzymes is said to be between 20-35°C.
The graph shows the effect of pH on a particular enzyme-controlled reaction. When is the enzyme not active? What happens to most enzymes above 60 °C? A They are denatured.
Enzymes work best at pH 7 because this is the pH of the body. The pH scale measures the concentration of hydrogen ions in solution.
As with many chemical reactions, the rate of an enzyme-catalysed reaction increases as the temperature increases. However, at high temperatures the rate decreases again because the enzyme becomes denatured and can no longer function. As the temperature increases so does the rate of enzyme activity.
Effect of Freezing on Enzyme ActivityAt very cold temperatures, the opposite effect dominates – molecules move more slowly, reducing the frequency of enzyme-substrate collisions and therefore decreasing enzyme activity.
Enzymes are proteins present in plants and animals. Freezing slows down, but does not destroy, enzymes in fruits and vegetables. That is why it is important to stop enzyme activity before freezing. The two methods you can use are blanching and adding chemical compounds such as ascorbic acid.
Heat, disease, or harsh chemical conditions can damage enzymes and change their shape. When this happens, an enzyme doesn't work anymore. This affects the body processes the enzyme helped support. For example, enzymes are required for proper digestive system function.
If the temperature is too far below or too high above this range, the enzyme stops working. Enzymes work fastest when they are at the optimum temperature, but as the temperature gets lower the enzyme's activity begins to decrease.
Enzymes are also subject to cold denaturation, leading to the loss of enzyme activity at low temperatures [11].
There are several factors that affect the speed of an enzyme's action, such as the concentration of the enzyme, the concentration of the substrate, temperature, hydrogen ion concentration (pH), and the presence of inhibitors.
Keeping the solution on ice makes the enzyme's activity decrease more slowly, giving you more time to do the experiment. If it is kept on ice, the solution should remain very active for 2 to 3 hours.
If you run a fever and your temperature increases too much, the structure of enzymes breaks down. They no longer function properly. Restoring your body temperature to its optimal range will help restore enzyme health.
At low temperatures enzymes are simply inactive. As temperature is increased the enzymes and substrate gain kinetic energy (move more quickly). This increases the frequency of collisions and the formation of enzyme-substrate complexes.
The bonds and interations making up the teriary structure of the enzyme are sensitive to heat. In different temperatures, these bonds can change. If an enzyme is used in the human digestive system (e.g. amylase), it will work best at body temperature of 37 degrees.
Why does reaction rate slow down drastically when temp is too high? The enzyme loses its shape (denatures) and can no longer effectively catalyze the reaction.
Optimal Growth ConditionsThus, a microbiologist will incubate a particular strain of bacteria at its optimal temperature so that he can study it when it is healthy. Organisms that grow best at human body temperature, which is approximately 37 degrees Celsius (98.6 degrees Fahrenheit), are called mesophiles.
