Enzymes have four levels of structures These are: 
* Primary structure * 
* Secondary structure * 
* Tertiary structure * 
* Quaternary structure

The enzyme structure ranges from a basic amino acid sequence to a three dimensional (3D) structure in a folded protein.Primary structure 
Enzymes are made up of amino acids which are linked together via amide (peptide) bonds in a linear chain.The amino acid sequence in polypeptide chains in each enzyme is distinct and determines the three-dimensional shape.This  ?is its tertiary structure

?quaternary structure  Sometimes, proteins or functional enzymes can be made up of more than one polypeptide chains, which are known as subunits.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.?Secondary structure ?