3 Carboxylic Ester Hydrolases

Krisch, K

doi:10.1016/s1874-6047(08)60086-4

Cited by 124 publications

(62 citation statements)

References 91 publications

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“…;1 rather broad protein band was obtained (Fig. 4), which is consistent with the presence of multiple (at least 4 irnd possibly more than 10) isoforms [4,12]. After electrophoresis.…”

Section: Isolation and Sequence Determination Ofporcine Liver Prolinesupporting

confidence: 71%

“…It also hydrolyzes some ester substrates at greater rates than L-proline-/?-naphthylamide [I]. On the other hand, carboxylesterase (EC 3.1.1,l) can hydrolyze various ester substrates such as p-nitrophenylacetate and was purified from microsomes of various organs such as liver, kidney and brain [4]. Among them, the porcine liver enzyme is the most extensively studied.…”

Section: Introductionmentioning

confidence: 99%

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The nucleotide and deduced amino acid sequences of porcine liver proline‐β‐naphthylamidase

et al. 1991

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A cDNA clone for porcine liver proline+-naphthylamidasc was isolated and sequenced. The deduced amino acid sequence of 567 residues was highly homologous with those of carboxylcsterases (EC 3. I. 1. I) previously reported for other species. In addition. proline-/I-naphthylamidase purified from porcine liver was shown to have strong activity towardsp-nitrophenylacetate. a representative substrate for carboxylesterases. These results suggest that proline-P-naphthylamidase is identical with carbouylrstrrase.

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“…;1 rather broad protein band was obtained (Fig. 4), which is consistent with the presence of multiple (at least 4 irnd possibly more than 10) isoforms [4,12]. After electrophoresis.…”

Section: Isolation and Sequence Determination Ofporcine Liver Prolinesupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

The nucleotide and deduced amino acid sequences of porcine liver proline‐β‐naphthylamidase

et al. 1991

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“…2 Krisch, 1971) and it has been proposed that the reaction mechanism may 28 require 2 interacting catalytic sites, or may involve substrate activation (Adler and Kistiakowsky, 1961). However, there is the added complication in our system of substrate diffusion across intact cell membranes, which could limit reaction rates and cause the initial upward concavity in substrate-dependent velocity has been described previously, and experiments are in progress to determine the cause.…”

Section: )Iscussionmentioning

confidence: 99%

Different esterase activities of exponential and plateau phases of EMT6 cells monitored by flow cytofluorimetry

Watson¹,

Workman²,

Chambers³

1978

Br J Cancer

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Summary.-The reaction rates of enzymes hydrolysing fluorescein diacetate have been studied in populations of intact tissue-culture EMT6, cells using flow cytofluorimetric techniques. It was found that the activity of these enzymes increased in plateau phases and that this correlated inversely with plating efficiency. Highly abnormal substrate-dependent reaction velocity kinetics were found in 14-, 21-, 28-and 35-day cultures. IN previous studies (Watson and Chambers, 1977) it has been shown that an enriched clonogenic fraction of EMT6 cells grown in vivo and separated by their ability to stick to plastic (Twentyman and Watson, 1977) has higher RNA levels than those cells which do not stick to plastic and which have a low plating efficiency. However, as the RNA distributions of the high and low clonogenic fractions overlapped, work was undertaken to find a second biochemical parameter which could be assayed simultaneously with RNA, in order to obtain a better discrimination between the 2 populations. Enzymes hydrolysing fluorescein diacetate can be assayed in populations of intact cells in suspension, using flow cytofluorimetric techniques and it was decided to study these enzymes to see whether hydrolysis rates could be utilized in conjunction with RNA measurements. The work presented in this communication compares the enzyme activities in populations of individual EMT6/M/CC cells during exponential growth and at 5 stages during the plateau phase and the results are related to changes in plating efficiency. MATERIALS AND METHODSEMT6/M/CC cells.-These are a variant of a mouse mammary tumour line (EMT6) (Rockwell, Kallman and Fajardo, 1972) which has been maintained in tissue culture for over 3 years in our laboratories. The preparation of single-cell suspensions and growth kinetic data have been reported previously by Twentyman et al. (1975). For these studies, cells were assayed during exponential growth and during the plateau phase at 7, 14, 21, 28 and 35 days after seeding the monolayer. Immediately before the enzyme assay, the monolayers were trypsinized and the cells were resuspended in medium at a concentration of 1-2 X 106/ml.Five separate experiments were carried out over a number of weeks. At each run, exponentially growing cells were assayed in parallel with one of the 5 ages of plateau phase. The culture medium was changed daily from Day 3 onwards in all plateauphase flasks. Plating efficiencies were also carried out in conjunction with the enzyme studies.Enzyme reaction.-The hydrolysis of fluorescein diacetate (FDA) is catalysed by a variety of hydrolytic enzymes, including lipase, acylase and a-and y-chymotrypsin (Guilbault and Kramer, 1966). We shall refer to these enzymes collectively as esterase. Activity

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“…One of the accepted classifications of esterases is by their inhibition properties (Meyers, 1960;Krisch, 1971;Walker and Mackness, 1983). Carboxylesterases are known to be serine hydrolases and therefore are strongly inhibited by organophosphorus compounds.…”

Section: Inhibitor Spec$citymentioning

confidence: 99%

“…Carboxyllesterases, the false target enzymes of insecticides, have both broad substrate specificities and distribution in the tissues of most organisms (Meyers, 1960;Krisch, 1971;Walker and Mackness, 1983). Carboxylesterases hydrolyse aliphatic and aromatic esters, as well as amides and thioesters, and are important in the metabolism of xenobiotics of the ester or amide type (Krisch, 1971;Dudman and Zemer, 1975; *Department of Chemistry, Central College, Bangalore University, Bangalore 560 001, India. tAuthor for correspondence.…”

Section: Introductionmentioning

confidence: 99%

Purification, characterization and properties of carboxylesterase from the midgut of the silkworm, Bombyx mori L.

Murthy

Veerabhadrappa

1996

Insect Biochemistry and Molecular Biology

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A carboxylesterase has been purified from the midgut of the silkworm Bonbyx mod L. by a combination of ammonium sulphate fractionation, DEAE-cellulose ion-exchange chromatography, Sephacryl S-200 gel-filtration and preparative polyacrylamide gel electrophoresis (PAGE). The homogeneity of the enzyme was established by PAGE, isoelectricfocusing (IEF) and SDS-PAGE. The enzyme consists of two identical subunits with a subunit molecular weight of 72,000. The two subunits are held by non-covalent bonds. Amino acid analysis of the purified enzyme revealed a high content of hydrophobic amino acid residues. It lacks proline and tryptophan residues and free thiol groups. The data from substrate specificity study in conjunction with kinetic parameters indicate the hydrophobic nature of the active site.

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3 Carboxylic Ester Hydrolases

Cited by 124 publications

References 91 publications

The nucleotide and deduced amino acid sequences of porcine liver proline‐β‐naphthylamidase

The nucleotide and deduced amino acid sequences of porcine liver proline‐β‐naphthylamidase

Different esterase activities of exponential and plateau phases of EMT6 cells monitored by flow cytofluorimetry

Purification, characterization and properties of carboxylesterase from the midgut of the silkworm, Bombyx mori L.

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