Answer:
If a tube incubated at 100°C showed no enzyme reaction, it's possible that the enzyme was denatured or inactivated at that high temperature.
Explanation:
Enzymes have specific temperature ranges, often referred to as their "optimum temperature," at which they function optimally. Operating at temperatures significantly above their optimum can lead to denaturation, where the enzyme loses its shape and function.
If the tube were later placed in its optimum temperature range, there's a possibility that the enzyme could regain its active conformation, allowing it to catalyze the reaction it's supposed to. However, this depends on several factors, including the degree of denaturation and the stability of the enzyme. In some cases, irreversible denaturation may occur, making the enzyme permanently inactive.
The specific outcome would depend on the enzyme in question and the conditions of denaturation. If the enzyme is stable and can recover its active state, there's a chance of a reaction occurring once it's returned to its optimum temperature range.