Answer;
-The secondary and tertiary structure of the enzyme.
Step-by-step explanation;
-Lactase is an enzyme that is found in the small intestine, liver, and kidney of mammals. In the presence of lactase, lactose is cleaved and reduced to its subunits D-galactose and D-glucose, monosaccharides that can eventually be utilized as a source of energy in cells.
-At extremely low pH, molecules move so slowly that reaction rates can be hampered even though the enzyme is still properly folded and active. At extremely high pH, bonds and interactions that exist between the amino acid side chains (R groups) in an enzyme become disrupted. The result is that the enzyme is incapable of maintaining its shape, and therefore unfolds, becoming inactive.