The factors that affect catalase activity are temperature, pH level and the concentration of the substrate. If any of these three factors are changed, the effectiveness of catalase to catalyze the decomposition of hydrogen peroxide will decrease.
Catalase is an enzyme that is vital to human, animal and plant life. It catalyzes the chemical decomposition of hydrogen peroxide into oxygen and water. Oxygen can actually be very dangerous because it is a very reactive element. Within the body, it likes to bond with water to create hydrogen peroxide, which means there is less oxygen gas is available. Catalase denatures that hydrogen peroxide constantly and turns it back into water and usable hydrogen gas. Catalase is an extremely efficient enzyme, and it is able to catalyze millions of hydrogen peroxide molecules in under a second.
In humans, catalase works best when the body is 98.6 degrees Fahrenheit and has a slightly basic pH. If either of these numbers goes up or down, such as during a fever, it means that the body is experiencing some sort of abnormality. When these factors change, catalase changes shape, which means that the hydrogen peroxide molecules do not fit as well into catalase's active site. The rate of reaction slows until the body returns to optimal temperature and pH level.