Chitinase: Restriction enzyme is used to separate DNA. But it is necessary that this DNA should be free from other macromolecules and must be in pure form. We know that DNA is surrounded by membranes. Therefore, the cell has to be broken in this. This process is done by special enzymes like lysozyme works to break down bacterial cells, cellulose works to break down plant cells and chitinase works to break down fungal cells. The fungal cell wall contains the chemical chitin, hence the enzyme that breaks down chitin is chitinase.