What happens to an enzyme’s activity at high temperatures?

Enzymes are proteins that act as biological catalysts, facilitating chemical reactions in living organisms. They function optimally within a specific range of temperature and pH. At high temperatures, the structure of the enzyme can become destabilized. This destabilization may lead to denaturation, where the enzyme's active site is altered, impacting its ability to bind to substrates effectively.

As temperature rises beyond this optimal level, the kinetic energy of the enzyme and substrate molecules increases, which can initially lead to an increase in reaction rates. However, once the temperature exceeds the enzyme’s optimal range, the adverse effects of denaturation dominate. As the enzyme loses its specific three-dimensional structure, its functionality decreases, possibly leading to a complete cessation of activity. Thus, an enzyme's activity decreases and may even stop altogether at high temperatures, as indicated in the correct answer.