What happens to enzymes at very high temperatures?

• A. They increase efficiency
• B. They become more effective at low pH
• C. They may denature and lose functionality
• D. They remain unchanged

Answer: (C)

Enzymes are proteins that facilitate biochemical reactions by lowering the activation energy required. Each enzyme has an optimal temperature range where it functions most effectively. At very high temperatures, the kinetic energy of the enzyme molecules increases. This can disrupt the delicate balance of non-covalent interactions, such as hydrogen bonds and ionic bonds, that maintain the enzyme’s three-dimensional structure.

When the temperature exceeds this optimal range, these interactions can break down, leading to a loss of structural integrity, a process known as denaturation. This change in structure alters the enzyme's active site, making it unable to bind its substrate effectively. As a result, the enzyme loses its functionality, which can significantly decrease the rate of the biochemical reactions it catalyzes. This phenomenon is crucial in biological systems, as extreme heat can dramatically hinder many metabolic processes.

The other choices do not accurately reflect the behavior of enzymes under high-temperature conditions. They do not enhance efficiency at high temperatures, do not change their effectiveness at low pH in this context, and certainly do not remain unchanged, as the temperature directly affects their structure and function. Understanding enzyme activity is vital in fields ranging from biochemistry to clinical diagnostics, where temperature control can impact experimental and therapeutic outcomes.