Lactase is an enzyme composed of a single polypeptide that hydrolyzes the disaccharide lactose to produce monosaccharides.The optimal pH for lactase activity is 6.Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity,likely due to the disruption of

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The optimal pH for lactase activity is 6 which means that the enzyme is most active at this pH. Transfer of lactase to pH 5 results in a substantial decrease in enzyme activity, which indicates that the enzyme has been denatured. Denaturation of an enzyme means that the protein structure has been disrupted such that the enzyme can no longer catalyze its reaction. Since the change in activity is significant, it is likely that the disruption affected the tertiary structure of the enzyme. The secondary structure may also be affected to some degree, but the denaturation of the quaternary structure is unlikely as lactase is a single polypeptide. Therefore, the best choice is C, which suggests that the disruption of the secondary and tertiary structures of the enzyme is responsible for the decrease in activity at pH 5.

Lactase Is an Enzyme Composed of a Single Polypeptide That