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Esterase
About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.
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TL;DR: Human esterase D (carboxylesterase; carboxylic-ester hydrolase, EC 3.1.1), a genetic marker of retinoblastoma, was purified to biochemical homogeneity from erythrocytes and expressed 3-fold in a promonocytic cell line treated with phenobarbital but not with phorbol myristate acetate, suggesting that ester enzyme D may have a role in detoxification.
Abstract: Human esterase D (carboxylesterase; carboxylic-ester hydrolase, EC 3.1.1.1), a genetic marker of retinoblastoma, was purified to biochemical homogeneity from erythrocytes. The purification scheme including carboxymethylcellulose, phenyl-Sepharose, chromatofocusing, and hydroxylapatite chromatographies resulted in a 10,000-fold purification of the enzyme with 15% recovery of total activity. The Km of esterase D was estimated to be 10 X 10(-6) M using 4-methylumbelliferyl acetate as substrate. The enzymatic activity was inhibited by p-chloromercuribenzoate and HgCl2, suggesting an important role of SH group(s) in enzyme function. Specific rabbit polyclonal and mouse monoclonal antibodies against esterase D were prepared and recognized either denatured or native human esterase D protein. Moreover, the polyclonal antibodies immunoprecipitated a polypeptide with a molecular mass of about 33-34 kDa from various cell lines of different mammalian species, indicating that the esterase D protein is highly conserved. The highest levels of this enzyme were found in liver and kidney. Furthermore, the expression of esterase D was enhanced 3-fold in a promonocytic cell line treated with phenobarbital but not with phorbol myristate acetate, suggesting that esterase D may have a role in detoxification. The availability of the homogeneous protein and its specific antibodies allows for cloning of the esterase D gene and facilitates studies of retinoblastomas.
62 citations
62 citations
TL;DR: It was concluded that the aspirin esterase activity of albumin is a pseudo-esterase activity in which aspirin stably acetylates lysines and releases salicylate.
62 citations
TL;DR: The present investigation was carried out for increasing the yield of tannase of Aspergillus niger and the physico‐chemical characterization of this enzyme, and tannic acid was the best substrate for three substrates tested, followed by methyl gallate and propyl gallate.
Abstract: The present investigation was carried out for increasing the yield of tannase of Aspergillus niger and the physico-chemical characterization of this enzyme. the extraction of enzyme protein. However, extraction of fungal pigments and proteins was observed to have high pH dependence, and maximum enzyme extraction was obtained at pH 5.5. The two-step purification protocol gave 51-fold purified enzyme with a yield of 20%. The total tannase activity was made up of nearly equal activity of esterase and depsidase. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of purified tannase protein indicated it to be made up of two polypeptides of molecular weight 102 and 83 kDa. Based on the Michaelis-Menten constant (Km) of tannase for three substrates tested, tannic acid was the best substrate with Km of 2.8 x 10(-4) M, followed by methyl gallate and propyl gallate. The inhibition was maximum for CaCl2 (58%) whereas EDTA had no modulatory effect on tannase activity. The inhibitor binding constant (KI) of CaCl2 was 5.9 x 10(-4) M Homogenization and detergent pretreatments did not have any remarkable effect on and the inhibition was of noncompetitive type.
62 citations
TL;DR: The A, B and C esterase bands showed variations in electrophoretic mobility which seemed to indicate an intraspecific differentiation of molecular structures of the ester enzyme that could have arisen during microbial evolution.
Abstract: SUMMARY: The intracellular esterases of 25 strains of Escherichia coli, growing exponentially on a minimal medium, were analysed by the acrylamide-agarose zymogram technique.
Five kinds of esterase bands were defined: three major bands (A, B and C) and two minor ones. The A and B esterase bands hydrolysed α-naphthyl, β-naphythl and indoxyl acetates; they were inhibited by di-iso-fluoropropyl phosphate (DFP). Esterase band B also hydrolysed the α- and β-naphthyl butyrates and was stable at 60°C. Esterase band C hydrolysed only β-naphthyl acetate and it resisted DFP. The A, B and C esterase bands showed variations in electrophoretic mobility which seemed to indicate an intraspecific differentiation of molecular structures of the esterase that could have arisen during microbial evolution.
62 citations