Cytosolic cholesterol ester hydrolase from bovine corpus luteum. Its purification, identification, and relationship to hormone-sensitive lipase.

The cytosolic cholesterol ester hydrolase from bovine corpus luteum has been purified 760-fold, using isoelectric precipitation and gel filtration chromatography, followed by ion-exchange and adsorption chromatographies in the presence of non-ionic detergent. Further purification was achieved by affinity chromatography on triacylglycerol-containing polyacrylamide-agarose. The partially purified enzyme was inhibited by NaF, HgCl2 and DFP. Incubation with [3H]DFP resulted in specific labelling of a polypeptide of Mr = 84000, the same subunit molecular weight as that of the enzyme from adrenal cortex. This Mr 84000 polypeptide from corpus luteum was phosphorylated by the catalytic subunit of cyclic AMP-dependent protein kinase, phosphorylation causing greater than 2-fold activation of the enzyme. Several properties of the cholesterol ester hydrolase from corpus luteum show striking similarities to those of hormone-sensitive lipase from adipose tissue. This provides further evidence that hormone-sensitive lipase, in addition to its role in adipose tissue lipolysis, has a key role in steroidogenic tissues, namely catalysing the supply of free cholesterol from the cholesterol ester stores.