They include the temperature and the pH value.
Each enzyme has a temperature range and pH range that makes them has the quickest action, they're called the optimum temperature and pH. Each optimum temperature and pH is different for each enzymes.
For example, the enzyme in our stomach has a optimum temperature of human temperature range, and a optimum pH for 2.0
However, if the temperature is too low or the pH value is too extreme, the enzyme may denature. The enzyme can no longer work to digests any substrate.
