Steryl ester hydrolase

Sterol acyltransferase (SGTase) and steryl ester hydrolase (SEHase)... 

Bouvier-Nave, R and Benveniste, P. (1995) Sterol acyl transferase and steryl ester hydrolase activities in a tobacco mutant which overproduces sterols. Plant Sci, 110, 11-9. 

The overall metabolism of vitamin A in the body is regulated by esterases. Dietary retinyl esters are hydrolyzed enzymatically in the intestinal lumen, and free retinol enters the enterocyte, where it is re-esterified. The resulting esters are then packed into chylomicrons delivered via the lymphatic system to the liver, where they are again hydrolyzed and re-esterified for storage. Prior to mobilization from the liver, the retinyl esters are hydrolyzed, and free retinol is complexed with the retinol-binding protein for secretion from the liver [101]. Different esterases are involved in this sequence. Hydrolysis of dietary retinyl esters in the lumen is catalyzed by pancreatic sterol esterase (steryl-ester acylhydrolase, cholesterol esterase, EC 3.1.1.13) [102], A bile salt independent retinyl-palmitate esterase (EC 3.1.1.21) located in the liver cell plasma hydrolyzes retinyl esters delivered to the liver by chylomicrons. Another neutral retinyl ester hydrolase has been found in the nuclear and cytosolic fractions of liver homogenates. This enzyme is stimulated by bile salts and has properties nearly identical to those observed for... 

A number of enzymes known as sulfuric ester hydrolases (EC 3.1.6) are able to hydrolyze sulfuric acid esters. They comprise arylsulfatase (sulfatase, EC 3.1.6.1), steryl-sulfatase (steroid sulfatase, steryl-sulfate sulfohydrolase, arylsulfatase C, EC 3.1.6.2), choline-sulfatase (choline-sulfate sulfohydrolase, EC 3.1.6.6), and monomethyl-sulfatase (EC 3.1.6.16). Whereas mono-methyl-sulfatase is highly specific and does not act on higher homologues, arylsulfatase has a broad substrate specificity and is of particular significance in the hydrolysis of sulfate conjugates of phenols, be they endogenous compounds, drugs, or their metabolites [167-169],... 

Phospholipids are hydrolysed by pancreatic phospholipase Aj (phosphatidylcholine 1-acylhydrolase) and phospholipase A2 (phosphatidylcholine 2-acylhydrolase) present as a zymogen that requires activation by trypsin. The products of 1,2-diacyl-s -glycero-3-phosphocholine breakdown are fatty acids and lysophospholipids, that is, 2-acyl-s -glycero-3-phosphocholine and l-acyl-s -glycero-3-phosphocholine, respectively. Cholesterol esters are hydrolysed by pancreatic steryl ester acylhydrolase (cholesterol ester hydrolase) to give cholesterol and fatty acids. 

A carboxylesterase (EC 3.1.1.1) from T. fusca [8, 86] and a steryl esterase (EC 3.1.1.13) from Melanocarpus albomyces [59] have also shown activity with PET oligomers and fabrics. The enzyme from M. albomyces with high specificity for fatty acid esters of sterols increased the hydrophilicity of PET fabrics. The highly hydrophobic serine hydrolase from T. fusca with a catalytic triad composed of serine, glutamic acid, and histidine hydrolyzed CTR and PET nanoparticles. The esterase showed high specificity towards short and middle chain-length fatty acyl esters of p-nitrophenol. In addition, p-nitrobenzyl esterases from Bacillus subtilis and B. licheniformis that hydrolyzed short chain dialkylphthalates and PET nanoparticles have been reported [74, 87]. 

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