Phospholipase D (phosphatidylcholine cholinehydrolase, EC 3.1.4.4) is a ubiquitous enzyme with a molecular weight of ~ 50,000Da. It is expressed in a variety of plant tissues, few microorganisms and some mammalian tissues.

Phospholipase D from Streptomyces chromofuscus has been used to cleave choline-containing phospholipids (PCs).

Phospholipase D (PLD) catalyses the hydrolysis of phosphatidylcholines (PC) to yield phosphatidic acid (PA) and choline. PC-PLD activity is regulated by hormones, cytokines, neurotransmitters and growth factors. Thus, it is considered to have a role in signal transduction in various cell types. Three vital lipid messengers produced by PLD plays a vital role in various crucial cellular processes and these lipids also have an essential role in downstream triglyceride and phospholipid synthetic pathway. PLD is essential for exocytosis in neurons and endocrine cells. In addition, it also plays a key role in phagocytosis.

Phospholipase D is active on sphingomyelins and lysophospholipids. Phospholipase D hydrolyzes the phosphate bonds of phospholipids and sphingomyelin to give the corresponding phosphatidic acid.

One unit will release 1 μmol of choline from L-α-phosphatidylcholine per hour at pH 8.0 and 30 °C.

Solution in 100 mM Tris/HCl, pH 8.0, 10% glycerol (v/v), and 0.1% Triton X-100 (w/v).