Final answer:
To determine the pH at which an enzyme exhibits 77% of its maximal activity, additional data or a graph illustrating the enzyme's activity across a range of pH levels is required, as it varies for each enzyme.
Step-by-step explanation:
The pH at which an enzyme shows 77% of maximal activity can vary significantly between different enzymes, as each has its own optimal pH. Typically, an enzyme shows maximal activity at its optimal pH and a decreased level of activity at pH levels above or below this optimal point.
For instance, if an enzyme has an optimum pH of 7.4, activity levels would be highest at this pH. Deviating from this pH will result in reduced enzyme activity. If you have data regarding how an enzyme's activity changes with pH (usually represented by a bell-shaped curve on a graph), you could estimate the pH at which the enzyme shows 77% of maximal activity by pinpointing where on the graph the enzyme's activity is 77% of the maximum.
Unfortunately, without a graph or additional data about how the enzyme's activity changes with pH, it's not possible to determine the exact pH at which an enzyme operates at 77% of maximum activity merely from the optimal pH value.