Enzyme activity is lost above about 45 degrees Celsius because
Correct answer: B. the enzyme is denatured as the weak bonds holding its tertiary structure break
- A. the substrate evaporates
- B. the enzyme is denatured as the weak bonds holding its tertiary structure break
- C. the enzyme is used up faster
- D. the activation energy increases
Explanation
Heat disrupts the hydrogen and ionic interactions that hold the chain in shape, so the active site loses its precise geometry and can no longer bind the substrate, and the loss is usually permanent. Below the optimum, raising the temperature increases the rate in the normal way, which is why the curve rises to a peak and then falls sharply. The peak for human enzymes lies near 37 degrees.
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About Enzymes as Biocatalysts
Enzymes are protein or RNA biocatalysts that lower activation energy without being consumed, and their active sites bind specific substrates. The topic covers the lock and key and induced fit models, effects of temperature, pH and substrate concentration, cofactors, enzyme specificity, and competitive versus non-competitive inhibition.
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