Protoplast

Protoplast in modern biology, is what is left of a cell when the cell wall is dissolved. That leaves the cell's nucleus and the surrounding protoplasmic materials.

Protoplasts of cells from a petunia's leaf

Protoplasts of Physcomitrella patens

Definition: a protoplast is a plant, bacterial or fungal cell that had its cell wall completely or partially removed using either mechanical or enzymatic means.

Because cell walls are made differently in the different kingdoms, different enzymes are used to remove them.

Enzymes for the preparation of protoplasts

Cell walls are made of a variety of polysaccharides. Protoplasts can be made by degrading cell walls with a mixture of the appropriate polysaccharide-degrading enzymes:

Type of cell	Enzyme
Plant cells	Cellulase, pectinase, xylanase
Gram-positive bacteria	Lysozyme (+EDTA)
Fungal cells	Chitinase

The reason for removing the cell walls is to allow many different experimental techniques to be used.

Protoplasts are widely used for DNA transformation (for making genetically modified organisms), since the cell wall would otherwise block the passage of DNA into the cell. In the case of plant cells, protoplasts can be regenerated into whole plants.