Human liver carboxylesterase

Junge, Wolfgang; Heymann, Eberhard; Krisch, K; Hollandt, H.

doi:10.1016/0003-9861(74)90304-x

Cited by 49 publications

(11 citation statements)

References 36 publications

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“…That additional reasons for the heterogeneity must exist has already been pointed out in the preceding paper [l]. It is remarkable that the carboxylesterase preparations obtained from ox [26, 271 and human liver [28] do not exhibit a comparable complex heterogeneity. In their kinetic properties both enzymes resemble the isoenzyme V of pig liver esterase.…”

Section: Discussionmentioning

confidence: 85%

Characterization of the Isoenzymes of Pig‐Liver Esterase 2. Kinetic Studies

Junge¹,

Heymann²

1979

European Journal of Biochemistry

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The kinetic properties of two of the partially separated isoenzymes I and V of pig liver esterase were studied. The cholinesterase-like isoenzyme I hydrolyses butyrylcholine as well as various other esters and aromatic amides. This isoenzyme is sensitive to 0.01 mM physostigmine and to fluoride. The second type (isoenzyme V) has the features of the so-called aliesterase: it acts preferentially on short-chain aliphatic esters, does not hydrolyse butyrylcholine and has only low activity towards amides. Further differences exist with regard to sensitivity towards organophosphorous inhibitors, to the influence of organic solvents and to the pH optimum. Transacylation reactions with methanol as an acceptor are mainly catalyzed by the isoenzyme of the aliesterase type.The esterase forms I11 and IV, which are located between isoenzymes I and V on the isoelectric focussing column, show kinetic features similar to those of a mixture of I and V. A stepwise increase or decrease, respectively, of certain kinetic properties, e.g. specific activities, is observed for the sequence I, 111, IV, V. A quantitative comparison of the kinetic properties supports our proposed subunit model [l], according to which the main components of these four esterase fractions are the trimers y y y , ayy, m y , and aaa.These results offer explanations for many of the very complex and often controversial results formerly obtained with the heterogeneous pig liver esterase.Kinetic studies on pig liver esterase have been carried out extensively in many laboratories [2 -71.

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Section: Discussionmentioning

confidence: 85%

Characterization of the Isoenzymes of Pig‐Liver Esterase 2. Kinetic Studies

Junge¹,

Heymann²

1979

European Journal of Biochemistry

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“…Previous studies (1,40) have reported on the purification of carboxylesterases from human liver tissue. The mutant carboxylesterase enzyme isolated from the culture media focused in the mid-pI range on a zymogram.…”

Section: Discussionmentioning

confidence: 99%

“…Generally, carboxylesterases exist as 60-kDa monomers, but a few associate to form homotrimers of approximately 180 kDa (1,2,15,16). cDNA clones have been obtained by screening gt11 expression libraries.…”

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confidence: 99%

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Expression and Partial Purification of a Recombinant Secretory Form of Human Liver Carboxylesterase

Miller

Scott

Chacko³

et al. 1999

Protein Expression and Purification

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“…Junge et al (2) reported that the molecular weight of hepatic esterase front humans was about :81,000-186,000 and the subunit weight was about 60,000.…”

Section: Substrate Specificity Of the Esterasementioning

confidence: 99%

Hydrolysis of Ester-Type Drugs by the Purified Esterase From Human Intestinal Mucosa

Inoue

Morikawa

Tsuboi

et al. 1979

Japanese Journal of Pharmacology

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Abstract-Esterase from human intestinal mucosa was purified 210 fold by solubilization with Triton X-100, chromatography on DEAF-cellulose, Sephadex G-100 and hydroxy lapatite, and isoelectric focusing. The purified esterase showed a single band by polyacrylamide gel electrophoresis.The molecular weight of the purified esterase was estimated to be about 55,000 by gel filtration on Sephadex G-150, and the isoelectric point was 5.02. The purified esterase was strongly inhibited by diethyl p-nitrophenyl phosphate (E-600) and diisopropyl fluorophosphate (DFP), and was not inhibited by eserine sulfate and p-chloromercuribenzoate.The purified esterase from human intestinal mucosa was found to be one of the carboxylesterases.The purified esterase hydrolyzed ester-type drugs, i.e., aspirin, clofibrate, indanyl carbenicillin and procaine, but did not hydrolyze amide-type drugs and choline-type drugs.Carboxylesterase hydrolyzing carboxyl esters, thiol esters and aromatic amides, are found in most animal tissues (1). The esterases have been purified from human liver and brain (2-3). There are however, only a few reports on intestinal esterases (4-5) and there are apparently few reports regarding these drug-metabolizing activities and detailed properties.We reported elsewhere that the intestinal estrase was present in the absorption site of the intestine, and the intestinal esterase differed characteristically from hepatic esterase (6).Furthermore, there was a difference in intestinal esterase activities among several species of animals (6). Human intestinal esterase hydrolyzes ester-type drugs to a large extent during absorption. Recently, a variety of estertype drugs is being used in many ways as prodrugs (7). Reported herein is the purification of esterase from human intestinal mucosa and examination of the enzyme properties. MATERIALS AND METHODS Crude EnzymeThe small intestine (jejunum) from humans was obtained at autopsy 12 hr after death.It was excised, shown to be non-pathologic, frozen and kept at -40'C until use . The intestinal mucosa was collected by scraping and was homogenized in Tris-mannitol medium;Tris-HC1 buffer (pH 7.4) containing 0.278 M mannitol at O 'C. Assay of Esterase ActivityEsterase and lipase activities were determined according to the methods described previously using /3-naphthyl derivatives, phenyl acetate (PA), tributyrin and olive oil as substrates (8-9). The esterase activities using acetylsalicylic acid (aspirin), ethylchloro phenoxyisobutyrate (clofibrate, CPIB) and indanyl carbenicillin (I-CBPC) as substrates were determined according to the methods described previously (6). Procaine and procainamide hydrolyzing activity was assayed at 37'C for 30 min by incubating with 1 mM procaine, procainamide as substrates and the product formed was determined according to the method of Tobin et al. (10). Acetanilide and phenacetin-hydrolyzing activity was determined by measuring the formation of aniline by the method of Krisch (11). Lidocaine-hydrolyzing activity was determined according to the met...

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Human liver carboxylesterase

Cited by 49 publications

References 36 publications

Characterization of the Isoenzymes of Pig‐Liver Esterase 2. Kinetic Studies

Characterization of the Isoenzymes of Pig‐Liver Esterase 2. Kinetic Studies

Expression and Partial Purification of a Recombinant Secretory Form of Human Liver Carboxylesterase

Hydrolysis of Ester-Type Drugs by the Purified Esterase From Human Intestinal Mucosa

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