Final answer:
The basis characteristic of the structure and location of enzymes is the presence of an active site where the enzyme binds to its substrates. This site contains specific amino acid residues that create a unique chemical environment for substrate binding.
Step-by-step explanation:
The basis characteristic of the structure and location of enzymes is the presence of an active site. The active site is where the enzyme binds to its substrates, which are the chemical reactants involved in the enzymatic reaction. It is usually a small region within the enzyme's primary, secondary, and tertiary structures, and contains specific amino acid residues that create a unique chemical environment suited for binding to specific substrates.