ABSTRACT
Phospholipases are a group of enzymes which hydrolyze phospholipids. There are five basic types of phospholipases, A, (EC 3.1.1.32), A2 (EC 3.1.1.4), B (EC 3.1.1.5), C (EC 3.1.4.10), and D (EC 3.1.4.4), which are classified according to the sites of their cleavage on phospholipid substrates. The occurrence of the various types of phospholipases has been presumed in plants. This chapter provides an overview on the current status of research on plant phospholipases. Phospholipase D (PLD) is a hydrolytic enzyme which releases an aminoalcohol head group such as choline from phospholipids. The various methods used for assaying phosphatidylcholinehydrolyzing phospholipase C (PLC) in plants include measuring inorganic phosphate released by a coupled alkaline phosphatase assay; using an artificial substrate, ρ-nitrophenolphosphocholine; and analyzing formation of diacylglycerol. The occurrence of PLC activity specific for inositol phospholipids has been documented in a number of plant species. The inositol phospholipid-specific PLC has been purified and its gene has been cloned from a number of mammalian tissues.
