Answer:
Enzymes are protein macromolecules. With the exception of catalytic DNA and RNA which are considered enzymes but not proteins.
They have a defined amino acid sequence, and are typically 100-500 amino acids long.
They have a defined three-dimensional structure.
Step-by-step explanation:
The three-dimensional structure of proteins is the primary structure of polypeptides, secondary structures in proteins (α-helix, β-sheet), and the tertiary structure.
Primary structure
Enzymes are made up of amino acids which are linked together via amide (peptide) bonds in a linear chain. This is the primary structure. The resulting amino acid chain is called a polypeptide or protein. The specific order of amino acid in the protein is encoded by the DNA sequence of the corresponding gene.
Secondary structure
The hydrogen in the amino group (NH2) and the oxygen in the carboxyl group (COOH) of each amino acid can bond with each other by means of hydrogen bond, this means that the amino acids in the same chain can interact with each other. As a result, the protein chain can fold up on itself, and it can fold up in two ways, resulting in two secondary structures: it can either wrap round forming the α-helix, or it can fold on top of itself forming the β-sheet.
Tertiary structure
As a consequence of the folding-up of the 2D linear chain in the secondary structure, the protein can fold up further and in doing so gains a three-dimensional structure. This is its tertiary structure.