Enzymes are a type of protein structure intended to change the chemical functions of odor molecules. There are basically six different classes of enzymes. However, within these six classifications there are around 10,000 different kinds of enzymes that all break down different kinds of molecules in order to change their chemical functions in one way or another. All of the six main classes of enzymes have a different reaction to the way they change cells and molecules. Once you determine what and how you want to change, the right enzymes with the right environmental conditions have to be found to reach the results you are looking for.