Enzymes are catalysts that increase the rate of a reaction by lowering the activation energy required for said reaction to occur spontaneously. The majority of enzymes are proteins, though enzymes can also be small RNA molecules, or ribozymes (Topic 3.1-Enzymes are True Catalysts). Enzymes are highly specific and are generally composed of 1 or more polypeptides that are folded into the most stable conformation, the native state. Also, enzymes require precise conditions in order to catalyze different types of reactions (Topic 3.2-Specificity, Tymoczko, J. L., Berg, J. M., & Stryer, L. 2013. p. 93-95). Physical and chemical factors that can affect an enzyme’s functionality and performance include, but are not limited to, (1) heat/temperature, (2) pH, (3) allosteric regulation, (4) the presence of cofactors, (5) the presence of inhibitors, and (6) the substrate concentration. These factors can change an enzyme’s environmental conditions and result in a change in enzymatic performance as enzymes may become denatured and/or may no longer be able to function properly/or as efficiently in their new conditions.
Enzymes operate within a specific temperature range for optimal performance. Depending on the enzyme and the type of reaction it catalyzes, the enzyme’s optimal temperature range may be a wide range or a narrow range. If the temperature of the enzyme’s environment is too low or too high, this can result in damage in the enzyme’s structure as the protein becomes denatured (Topic 2.3-Denaturation and Its Effect on Structure). Consequently, the enzyme may be unable to resume its original conformation, thereby losing its functionality and halting catalytic activity (Tymoczko et al., 2013. p. 126-127).
pH can greatly affect the ability of an enzyme to function as well. Similar to heat thresholds, most enzymes have a specific pH range that they optimally perform at. If the pH is too low or too high, this can denature the enzyme and result in a nonfunctional enzyme. For example, most enzymes are unable to exist in highly acidic conditions. However, pepsin, an enzyme in the stomach, has an optimal pH near 2, whereas chymotrypsin, a pancreatic enzyme has an optimal pH near 8 (Tymoczko et al., 2013. p. 127).
Regulatory molecules involved in allosteric regulation can alter the equilibrium between the relaxed (R) state and the tense (T) state of the allosteric enzyme. Consequently, regulation can control an enzyme’s performance by regulating its catalytic activity (Allosteric Regulation, n.d). If a positive effector binds to an R form, it stabilizes it and increases the likelihood of the substrate binding to S. Thus, the positive effector lowers the threshold concentration needed for enzymatic activity. In comparison, if a negative effector binds to a T form and stabilizes it, this will increase the T concentration and reduce the likelihood of R binding to the substrate. Thus, the negative effector increases the threshold...