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PubMed1998

The defense-related rice gene Pir7b encodes an alpha/beta hydrolase fold protein exhibiting esterase activity towards naphthol AS-esters.

Acquired resistance of rice to Pyricularia oryzae, the causing agent of rice blast, can be induced by inoculation with the non-host pathogen Pseudomonas syringae pv. syringae. We have previously cloned a cDNA and a corresponding gene (Pir7b) whose transcripts accumulate upon infiltration with the resistance-inducing bacteria. The putative encoded product Pir7b exhibits significant sequence similarity to two recently cloned hydroxynitrile lyases from Manihot esculenta (cassava) and Hevea brasisliensis, enzymes involved in the release of hydrogen cyanide from cyanogenic glycosides. As rice does not contain cyanogenic glycosides, a similar function of Pir7b appears unplausible. In order to functionally characterize the protein, recombinant Pir7b was produced in Escherichia coli and Saccharomyces cerevisiae. We show that recombinant Pir7b does not have hydroxynitrile lyase activity, but exhibits esterase activity towards naphthol AS-acetate. Using Pir7b-specific antibodies, we show that the protein accumulates in rice leaves inoculated with P. syringae pv. syringae. Both the recombinant and the authentic proteins have an apparent molecular mass of 32 kDa (28.8 kDa calculated) and seem to be active as monomers. Pir7b esterase also exhibits sequence similarity to several expressed sequence tags of Arabidopsis thaliana, indicating that it belongs to a family of proteins widely occuring in plants.

Amino Acid Sequence↗
PubMed2000

A novel extracellular esterase from Bacillus subtilis and its conversion to a monoacylglycerol hydrolase.

A novel gene lipB, which encodes an extracellular lipolytic enzyme, was identified in the Bacillus subtilis genomic DNA sequence. We have cloned and overexpressed lipB in B. subtilis and Escherichia coli and have also purified the enzyme from a B. subtilis culture supernatant to electrophoretic homogeneity. Four different lipase assays were used to determine its catalytic activity: pH-stat, spectrophotometry, fluorimetry and the monomolecular film technique. LipB preferentially hydrolysed triacylglycerol-esters and p-nitrophenyl-esters of fatty acids with short chain lengths of </= 10 carbon atoms. Triolein, which is a typical substrate for true lipases, was not hydrolysed at all. These results led us to classify LipB as an esterase rather than a lipase. The catalytic triad of LipB consists of residues Ser78, Asp134, and His157 as demonstrated by amino-acid sequence alignments and site-directed mutagenesis. The nucleophile Ser78 is located in a lipase-specific consensus sequence, which is Ala-X-Ser-X-Gly for most Bacillus lipases. All other bacterial lipases contain a glycine residue instead of the alanine at position-2 with respect to the catalytic serine. We have investigated the role of this alanine residue by constructing LipB variant A76G, thereby restoring the lipase-specific consensus motif. When compared with LipB this variant showed a markedly reduced thermostability but an increased stability at pH 5-7. Determination of the specific activities of wild-type LipB and variant A76G using a monomolecular film of the substrate monoolein revealed an interesting result: the A76G substitution had converted the esterase LipB into a monoacylglycerol hydrolase.

Amino Acid Sequence↗
PubMed1975

[Eosinophilic leukaemia with chloroacetate-esterase-positive granules in a child (author's transl)].

Eosinophilic leukaemia was diagnosed in a 13-year-old boy with clinical and haematological signs of acute leukaemia. A positive naphthol-AS-D-chloroacetate esterase reaction was present in 93% of bone marrow eosinophils. This confirms earlier findings for this sub-group of leukaemia in adultsmcharcot-Leyden's crystals were found in bone marrow, and the eosinophils were further characterized by other cytochemical and electronmicroscopic studies. Only short remission periods were achieved, the patient dying 53 weeks after diagnosis. Attacks of cardiac arrhythmias, thought to be due to adriamycin treatment, were probably related to thrombi in the coronary arteries as a result of disseminated intravascular coagulation. It is thought that eosinophilic leukaemia with a positive naphthol-AS-D-chloroacetate esterase reaction is a variant of acute myeloid leukaemia.

Acute Disease↗
PubMed1982

Nonoxidative ethanol metabolism: formation of fatty acid ethyl esters by cholesterol esterase.

The recent identification of myocardial metabolites of ethanol--fatty acid ethyl esters--suggests that some of the pathophysiological derangements associated with alcohol-induced heart muscle disease may be a consequence of products of myocardial ethanol metabolism. The donor of the fatty acid moiety in the formation of fatty acid ethyl esters has been identified as nonesterified fatty acid. Fatty acid esterification with ethanol is shown to be mediated by cholesterol esterase (sterol-ester acylhydrolase, EC 3.1.1.13), a finding that identifies a singular nonoxidative ethanol metabolism by an enzyme. A potential basis for the protective effect of ethanol ingestion on atherogenesis is also suggested because fatty acid ethyl esters inhibit cholesterol esterification catalyzed by pancreatic cholesterol esterase and hepatic and aortic microsomal fatty acyl-CoA:cholesterol O-acyltransferase (EC 2.3.1.26).

Animals↗
PubMed1988

Molecular cloning of an inducible serine esterase gene from human cytotoxic lymphocytes.

A cDNA clone encoding a human serine esterase gene was isolated from a library constructed from poly(A)+ RNA of allogeneically stimulated, interleukin 2-expanded peripheral blood mononuclear cells. The clone, designated HSE26.1, represents a full-length copy of a 0.9-kilobase mRNA present in human cytotoxic cells but absent from a wide variety of noncytotoxic cell lines. Clone HSE26.1 contains an 892-base-pair sequence, including a single 741-base-pair open reading frame encoding a putative 247-residue polypeptide. The first 20 amino acids of the polypeptide form a leader sequence. The mature protein is predicted to have an unglycosylated Mr of approximately equal to 26,000 and contains a single potential site for N-linked glycosylation. The nucleotide and predicted amino acid sequences of clone HSE26.1 are homologous with all murine and human serine esterases cloned thus far but are most similar to mouse granzyme B (70% nucleotide and 68% amino acid identity). HSE26.1 protein is expressed weakly in unstimulated peripheral blood mononuclear cells but is strongly induced within 6-hr incubation in medium containing phytohemagglutinin. The data suggest that the protein encoded by HSE26.1 plays a role in cell-mediated cytotoxicity.

Amino Acid Sequence↗
PubMed1990

Molecular analysis of evolutionary changes in the expression of Drosophila esterases.

Drosophila melanogaster transformed with the esterase 5 (Est-5) gene from Drosophila pseudoobscura were used to assess the evolutionary basis for differences in the sex- and tissue-specific expression of the esterase 5 (EST 5) enzyme in D. pseudoobscura relative to its homologue in D. melanogaster, EST 6. EST 5 is expressed in the eyes and hemolymph of transformed D. melanogaster just as it is in D. pseudoobscura, but it is not detectable in the ejaculatory duct, where the homologous enzyme, EST 6, is most abundant. EST 5 also occurs at equal levels in both sexes of the transformants and D. pseudoobscura, whereas EST 6 is more abundant in male than in female D. melanogaster. Northern analysis of transformed and untransformed flies indicates that the expression patterns of EST 5 and EST 6 are controlled at the level of transcription and suggests that regulatory differences between Est-6 and Est-5 have evolved mainly through cis-acting regulatory changes in the two loci rather than through alterations in trans-acting factors. Equal expression of EST 5 in male and female transformants also indicates that the X-chromosome-linked Est-5 gene of D. pseudoobscura, when isolated as a 4.5-kilobase restriction fragment, is not dosage compensated after integration into an autosome of D. melanogaster.

Animals↗
PubMed1968

The enzymatic nature of C'1r. Conversion of C'1s to C'1 esterase and digestion of amino acid esters by C'1r.

Human C'1, a macromolecular complex composed of three subunits, is the zymogen for at least two distinct enzymes. Preparations of one subunit, C'1r, functioned as a protease which converted another subunit, C'1s, to C'1 esterase. The conversion of C'1s to C'1 esterase by C'1r was blocked by Liquoid, phenyl methylsulfonyl fluoride, and calcium ions, but not by soybean trypsin inhibitor, hirudin, or heparin. Preparations of C'1r also possessed two additional functions, i.e., the ability to hydrolyze certain synthetic amino acid esters and to participate in immune hemolysis. Evidence was presented which indicates that these three functions are properties of a single entity, C'1r, but not of the same portion of its molecular structure. These observations suggest that C'1r has at least two active sites, one for its reaction with C'1q, an additional subunit of C'1, and one for its reaction with C'1s; together, the three subcomponents, C'1q, C'1r, and C'1s, form a single functional unit, the first component of complement.

Amino Acids↗
PubMed1991

Expression of perforin and serine esterases by human gamma/delta T cells.

gamma/delta T cells have recently been described in association with a number of disorders, including autoimmune diseases. gamma/delta T cells are thought to play a cytotoxic role, but their mechanism of action is not known. Several granule mediators of cytotoxicity, including a pore-forming protein (perforin), and a family of serine esterases, have been isolated from cytotoxic T lymphocytes (CTL), lymphokine-activated killer (LAK) cells, and natural killer (NK) cells. We demonstrate here that gamma/delta T cells also express these mediators. Northern blots show that gamma/delta T cells express perforin, serine esterase 1 (SE 1), and SE 2. Three polyclonal antisera - raised against murine perforin, a peptide composed of amino acids 1-34 of human perforin, and human peforin expressed in bacteria - all reacted with a 70-kD protein in gamma/delta T cells on Western blots. Immunostaining with antiperforin antisera shows that primary gamma/delta T cells also contain perforin. Electron microscopy reveals that the granules of gamma/delta T cells resemble those of CTL, LAK, and NK cells. Gamma/delta T cells also resemble LAK cells in possessing inclusion bodies in their nuclei. These results imply that gamma/delta T cells resemble other cytolytic lymphocytes in their mechanism of action.

Blotting, Northern↗
PubMed1981

Acute lymphocytic leukemia with prominent azurophilic granulation and punctate acidic nonspecific esterase and phosphatase activity.

Cytochemical, ultrastructural, and terminal deoxynucleotidyl transferase determinations in three cases of acute lymphocytic leukemia with azurophilic granules and punctate alpha-naphthyl acetate esterase (ANAE), alpha-naphthyl butyrate esterase (ANBE), and acid phosphatase (AP) activities further described a cytochemical and morphologic variant of acute lymphocytic leukemia. The ANAE, ANBE, and AP activities appeared specially localized within cytoplasmic granules. Electron microscopy substantiated a prominence of membrane-bound dense-core cytoplasmic granules. The variegated appearance of these dense-core granules and the cytochemical profile suggest that the aberrant granules are lysosomal in nature. Both the prominent cytoplasmic granules and the older age distribution led to early misdiagnosis of myelocytic leukemia. The distinctive cytochemical/morphologic profile and the ease of misdiagnosis suggest an important morphologic variant of acute lymphocytic leukemia.

Adolescent↗
PubMed1982

Acid phosphatase and alpha-naphthyl acetate esterase in neoplastic and non-neoplastic lymphocytes. A statistical analysis.

Acid phosphatase and alpha-naphthyl acetate esterase reaction patterns were evaluated in lymphocytes from patients with a variety of neoplastic and non-neoplastic conditions: leukemia, 59; NHL, 53; and reactive follicular hyperplasia, 23. Fifteen individuals with normal peripheral blood were also studied. For both enzymes, statistical analysis showed a strong correlation between a globular reaction pattern and T lymphocytic origin in both non-neoplastic lymph nodes and normal peripheral blood specimens (P less than 0.0001). A similarly strong correlation was found between a granular acid phosphatase pattern and T lymphocytic origin in cell isolated from non-neoplastic lymph nodes (P less than 0.0001) but not in those obtained from normal peripheral blood where this pattern was observed with equal frequency in B, T, and "null" lymphocytes (P = 0.415). A granular alpha-naphthyl acetate esterase pattern was correlated with non-T lymphocytes from normal peripheral blood (P less than 0.0001), but was observed with equal frequency in B, T, and "null" lymphocytes fron non-neoplastic lymph nodes (P = 0.76). In the eight T cell neoplasias studied, a globular pattern was evident in the majority of cells for both enzymes. In the majority of the B cell neoplasias, however, a granular pattern was observed for both enzymes.

Acid Phosphatase↗
PubMed2004

Putative odorant-degrading esterase cDNA from the moth Mamestra brassicae: cloning and expression patterns in male and female antennae.

An esterase cDNA was isolated from the cabbage armyworm Mamestra brassicae antennae by PCR strategy. The full-length cDNA, designated as Mbra-EST, contains a 1638 bp open reading frame encoding a predicted protein of 546 amino acids. This predicted protein presents the structural characteristics of known insect carboxyl-esterases, in particular the Ser-His-Glu catalytic triad. The expression pattern of the gene was studied by RT-PCR, Northern-blot and in situ hybridization. The ribosomal protein rpL8 gene from M. brassicae was also cloned to obtain a normalized tool for the comparative gene expression studies. Mbra-EST transcripts are specifically expressed in the antennae of males and females and in the proboscis of males. In antennae of both sexes, expression is restricted to the olfactory sensilla trichodea, suggesting a role in degradation of odorant acetate compounds, such as pheromones as well as plant volatile acetate components.

Amino Acid Sequence↗
PubMed1996

Is esterase-P encoded by a cryptic pseudogene in Drosophila melanogaster?

We have amplified and sequenced the gene encoding Esterase-P (Est-P) in 10 strains of Drosophila melanogaster. Three premature termination codons occur in the coding region of the gene in two strains. This observation, together with other indirect evidence, leads us to propose that Est-P may be a pseudogene in D. melanogaster. Est-P would be a "cryptic" pseudogene, in the sense that it retains intact the coding sequence (without stop codons and other alterations usually observed in pseudogenes) in most D. melanogaster strains. We conjecture that the beta-esterase cluster may consist in other Drosophila species of functional and nonfunctional genes. We also conjecture that the rarity of detected pseudogenes in Drosophila may be due to the difficulty of discovering them, because most of them are cryptic.

Amino Acid Sequence↗
PubMed1975

Esterase gene frequency differences and linkage equilibrium in Drosophila virilis populations from different ecological habitats.

In order to study the gene frequency and linkage equilibrium in natural populations, about 5740 chromosomes of Drosophila virilis flies from eight natural populations were analyzed by the null strain method for two linked esterase loci. The frequencies of these esterase genes appear to depend on habitat characteristics rather than on geographical distribution. The populations kept a high degree of linkage equilibrium among them (D-.005).

Animals↗
PubMed1981

Genetic variability at the esterase-6 locus in natural populations of Drosophila simulans in relation to environmental heterogeneity.

The allozymic variation at at the esterase-6 locus examined in fourteen samples of natural populations of Drosophila simulans collected in two different localities. The samples were collected from different species of fruits in the two localities and from banana baits located some meters apart from the fruits. The analysis was done by sequential electrophoresis, using varied gel concentrations and buffers. By this technique, we detected 27 alleles at the esterase-6 locus, where only five alleles were detected by the usual method. The results obtained suggest that habitat choice alone may not be a selective factor, but may be selective in combination with other environmental factors.

Alleles↗
PubMed1981

Esterase dependence of human neutrophil functions: lysozyme secretion, spontaneous migration, and continuity of the respiratory burst.

To assess the esterase dependency of human neutrophil secretion of lysosomal enzyme, the influence of several aromatic amino acid esters on phorbol myristate acetate-induced release of lysozome was studied. This function was found to be esterase-dependent on the basis of the inhibitory influence of such esters. Of the esters tested, tryptophan octyl ester, tryptophan benzyl ester, benzoyl tyrosine ethyl ester, and tryosine methyl ester were the most potent inhibitors of this response, being effective in the order listed. All esters with inhibitory effects were active at concentrations of less than or equal to 100 muM. Other neutrophil functions found to be similarly sensitive to the presence of these esters were spontaneous and chemotactic migration an continuity of the respiratory burst. The common inhibition profile of these neutrophil activities by the esters used suggests the activity of a common enzyme in these various functions.

Amino Acids↗
PubMed2005

Entropy and GC Content in the beta-esterase gene cluster of the Drosophila melanogaster subgroup.

We perform spectral entropy and GC content analyses in the beta-esterase gene cluster, including the Est-6 gene and the psiEst-6 putative pseudogene, in seven species of the Drosophila melanogaster species subgroup. psiEst-6 combines features of functional and nonfunctional genes. The spectral entropies show distinctly lower structural ordering for psiEst-6 than for Est-6 in all species studied. Our observations agree with previous results for D. melanogaster and provide additional support to our hypothesis that after the duplication event Est-6 retained the esterase-coding function and its role during copulation, while psiEst-6 lost that function but now operates in conjunction with Est-6 as an intergene. Entropy accumulation is not a completely random process for either gene. Structural entropy is nucleotide dependent. The relative normalized deviations for structural entropy are higher for G than for C nucleotides. The entropy values are similar for Est-6 and psiEst-6 in the case of A and T but are lower for Est-6 in the case of G and C. The GC content in synonymous positions is uniformly higher in Est-6 than in psiEst-6, which agrees with the reduced GC content generally observed in pseudogenes and nonfunctional sequences. The observed differences in entropy and GC content reflect an evolutionary shift associated with the process of pseudogenization and subsequent functional divergence of psiEst-6 and Est-6 after the duplication event.

Animals↗
PubMed1988

Structures of sugar chains of a p-nitrophenyl acetate-hydrolyzing esterase from the microsomes of rat liver.

The structures of sugar chains of a p-nitrophenyl acetate-hydrolyzing esterase from the microsomes of rat liver were established. The enzyme contained mannose and glucosamine as sugar components. Asparagine-linked sugar chains of the esterase were liberated by hydrazinolysis. After N-acetylation of the hydrazinolysate, the reducing ends of the sugar chains were coupled with 2-aminopyridine. Fluorescent pyridylamino (PA-) derivatives of sugar chains thus obtained were purified by gel filtration and reversed-phase HPLC. Eleven PA-sugar chains were obtained. The structures of the PA-sugar chains were first identified by HPLC using two series of separation systems by which 11 PA-oligomannose-type sugar chains with known structures could be separated. Further elucidation of the structures of each PA-sugar chain was performed by exoglycosidase digestions and partial acetolysis. The structures of two of the PA-sugar chains were further confirmed by 500 mHz 1H-NMR spectroscopy.

Animals↗
PubMed1975

A simple rapid separation of C1-esterase using an immunoadsorbent column.

An immunoadsorbent-antibody (egg albumin-Sepharose-antibody) column was found to be suitable for the rapid separation of C1-esterase from normal human serum. About 1.54 mg of C1-esterase, with a specific activity of 447 units/mg was obtained in voer 80% yield from the 20 ml of human serum.

Adsorption↗