Why is the tertiary structure of maltase essential to its function?

A good starting point in this question is identifying what is meant by the ‘tertiary structure’ of a protein, which is the folding of the protein into its 3D structure/shape. Relate this ten to maltase – an enzyme (contains an active site). You can therefore say that the tertiary structure of maltase determines the shape of its active site, which is complementary in shape to a specific substrate, in this case – maltose. To get the final mark, you could think – what would happen if the active site changes its shape? - the substrate no longer fits into its active site and the enzyme-substrate complex can no longer form.