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PubMed1987

Enzymatic hydrolysis of diethylpyrocarbonate, a commonly used histidine modifying agent, by esterases.

Diethylpyrocarbonate, a reagent commonly used to modify active site histidines in enzymes, was found to be hydrolyzed by several esterases. Two of these, cutinase, a typical serine esterase from the fungus Fusarium solani pisi, and thioesterase B from the uropygial gland of the mallard duck Anus platyrhynchus, hydrolyzed diethylpyrocarbonate so rapidly that histidine modification could not be detected except when the enzymic activity was inhibited by diisopropylfluorophosphate treatment or by the presence of critical micellar concentrations of sodium dodecyl sulphate. Possible loss of diethylpyrocarbonate should be of concern when this reagent is used to test for available histidines in hydrolytic enzymes.

Animals↗
PubMed1977

Strain differences in response to dietary cholesterol by JAX rabbits: correlation with esterase patterns.

Six strains of genetically defined JAX rabbits were tested for their serum cholesterol levels (total and free) in response to a 0.5% cholesterol diet. Marked differences in response between the 6 strains were found. IIIVO/J and WH/J are low responding strains, X/J and ACEP/J are intermediate responding strains, and OS/J and AX/J are high responding strains. After 4 weeks of the cholesterol diet the total serum cholesterol level of the high responding AX/J strain was about 5-fold greater than the level of the low responding IIIVO/J strain. The esterified/total (E/T) ratio appeared to be higher in the high responding strains, indicating a synergistic effect in the process of atherosclerosis. The response of the individual rabbits to the cholesterol diet was compared with the patterns of serum and liver esterase zymograms. This comparison indicated a correlation of the dietary cholesterol susceptibility with the presence or absence of the esterase zones in the anodal, fast moving region of the gel.

Animals↗
PubMed1982

Sex differences in aortic cholesterol esterase activity in rats, and changes of the activity following castration and gonadal hormone treatment.

Sex differences in aortic cholesterol esterase activity and changes in the activity following castration and gonadal hormone treatment were investigated in rats. Differences in the enzyme activity were apparent after 2.5 months and became most significant after 6 months. The activity in the aorta and the liver was significantly higher in female rats. Prepubertal orchiectomy increased the aortic activity, feminizing the type of metabolism, whereas postpubertal orchiectomy, and both pre- and postpubertal ovariectomy induced no change in the activity. The administration of testosterone to female rats significantly decreased the aortic activity, masculinizing the type of metabolism. However, the administration of testosterone or of 17 beta-estradiol to male rats had no effect. These results suggest (1) that there are clear sex differences in aortic cholesterol esterase activity, (2) that prepubertal exposure to androgens plays a critical role in the sexual differentiation in aortic and hepatic cholesterol ester metabolism, and (3) that the administration of testosterone can temporarily masculinize the type of metabolism. These results partly explain the sexual differences in susceptibility to atherosclerosis.

Aging↗
PubMed1986

The use of three esterase kits to measure plasma cholesterol concentration in the rat and three other species.

Three enzymatic methods for the determination of cholesterol and its esters were applied to plasma samples obtained from normocholesterolaemic rats, dogs, rabbits and man. A major difference was observed for rat plasma values, where the results obtained with a microbial esterase for the hydrolysis of cholesteryl esters were much lower than those obtained with mammalian esterases. This difference was greater for rats than for the other three species studied and is probably related to the plasma distribution of lipoproteins in the rat.

Animals↗
PubMed1992

Crystallization and preliminary crystallographic data of a Streptomyces scabies extracellular esterase.

X-ray quality single crystals of an extracellular esterase from pathogenic Streptomyces scabies were obtained by the hanging drop method. The crystals are monoclinic (space group C2, a = 161.1 A, b = 51.2 A, c = 124.2 A, beta = 100.6 degrees) with two molecules related by a noncrystallographic dyad in the asymmetric unit, with a solvent content of approximately 64%. The diffraction pattern from fresh crystals extends beyond 2 A resolution using sealed tube CuK alpha radiation. The study has been initiated in order to elucidate the mechanism of this unusual non-serine-dependent esterase, and to gain better understanding of the molecular basis of the pathogenesis of the scab disease.

Crystallization↗
PubMed1977

A fluorigenic substrate for the rapid differentiation of Mycobacterium fortuitum from Mycobacterium chelonei on the basis of heat stable esterase activity.

A fluorigenic substrate, 4-methylumbelliferyl butyrate, enables mycobacterial esterase activity to be easily and rapidly detected and quantitated. By use of this substrate, the esterase activity of Mycobacterium fortuitum was found to be significantly more heat resistant than that of M. chelonei. On this basis, a rapid, simple and inexpensive test for the differentiation of these two species has been developed.

Bacteriological Techniques↗
PubMed1983

A two-site model for the esterase and dehydrogenase activities of sheep liver aldehyde dehydrogenase.

Although aldehyde dehydrogenase (ALDH) from sheep liver cytosol has a broad specificity, it will not oxidize the aldehyde group of glyoxylic acid which is in fact an inhibitor of the enzyme. The inhibition pattern is non-linear but competitive at high propionaldehyde concentrations (2-20 mM); however, a simple non-competitive pattern is observed at low (less than 100 microM) propionaldehyde concentrations (Ki = 1.6 mM). The esterase activity was unaffected by glyoxylic acid in the absence of NAD+ but a simple competitive inhibition pattern (Ki = 2.5 mM) was observed with respect to 4-nitrophenyl acetate in the presence of NAD+. The data require a two-site model in which ester and aldehyde binding sites are distinct but with a second propionaldehyde molecule, and glyoxylic acid, binding at or near the ester binding site. Consistent with this model is the fact that chloral hydrate was a non-competitive inhibitor of the esterase activity in the presence of NAD+ but a competitive inhibitor in its absence. The enzyme exhibited hysteretic behavior governed by the protonated form of an ionizable group with an apparent pKa of 7.55.

Aldehyde Dehydrogenase↗
PubMed1987

A family of serine esterases in lytic granules of cytolytic T lymphocytes.

Cytoplasmic granules of cytolytic T lymphocytes (CTLs) contain, in addition to the pore-forming protein perforin, a family of highly homologous serine esterases, granzymes A-H. The serine esterase affinity label diisopropyl fluorophosphate reacts strongly with granzymes A and D, to a lesser extent with B, E, F, G, and H, and not at all with C and F. For granzymes A and D, synthetic substrates have been found. Antibodies raised against granzyme B strongly cross-react with A, G, and H, and antibodies to granzyme D recognize C, E, and F. These antigenic relationships correlate with similarities in the N-terminal amino acid sequences. At least 60% homology is observed between the eight proteins, and all are similar to rat mast cell protease 2. Sequence analysis suggests the identity of granzyme A with a protease predicted from a CTL-specific cDNA clone (H factor) and of granzyme B, G, or H with a protein encoded by the CTL-specific cDNA clone CTLA 1/CCP 1.

Amino Acid Sequence↗
PubMed1996

A new esterase for the cleavage of pivalic acid-containing prodrug esters of cephalosporins.

An extracellular esterase from the actinomycetes Amycolatopsis orientalis was found by screening. It is capable of splitting the isomeric mixture (K/J) of (I, Scheme 1) into 7-amino-3-methoxymethyl-3-cephem-4-carboxylic acid, pivalic acid, and acetaldehyde with a high yield. The purified enzyme of 55.4 Kd by SDS-PAGE shows an N-terminal sequence of VRTCADLVRTYDLPGAVTH. The isoelectric point is 8.9 +/- 0.1. It can be immobilized with good yield to VA-Epoxy Biosynth. Besides the above-mentioned reaction, the esterase cleaves many other esters such as methyl-2-chloropropionic acid.

Actinobacteria↗
PubMed1992

Fluid pinocytosis and esterase-oxidase in chronic myeloid leukemic granulocytes are differentially stimulated by chemotactic peptide.

Binding of a chemotactic peptide, n-formyl-methionyl-leucyl-phenylalanine (FMLP) to polymorphonuclear leukocytes (PMNL) leads to a series of biochemical and functional events. We have studied stimulation of fluid phase pinocytosis (FP), esterase and oxidase by FMLP in CML PMNL, by flow cytometry. Stimulation of FP in CML PMNL was lower than that in normal PMNL but, stimulation of esterase and oxidase was comparable to that in normal PMNL. Thus, early response to FMLP which is dependent on the integrity of actin network seems to be defective in CML PMNL.

Chemotaxis, Leukocyte↗
PubMed1983

In vitro properties of diffuse cytoplasmic esterase-positive canine mononuclear leukocytes.

Depletion of cytoplasmic esterase-positive canine peripheral blood monocytes from mononuclear cell suspensions was attempted using plastic adherence, carbonyl iron ingestion and/or Sephadex G-10 filtration. An esterase-positive, nonadherent, nonphagocytic subpopulation was identified and further characterized by the presence or absence of cell membrane receptors for the Fc portions of immunoglobulin and the activated third component of complement. The majority of these nonadherent cells lacked these receptors. The data suggests that canine peripheral blood monocytes are a heterogenous cell population.

Adhesiveness↗
PubMed1990

An evaluation of the mononuclear cells derived from bovine mammary gland dry secretions using leukocyte antigen specific monoclonal antibodies, light scattering properties and non-specific esterase staining.

The distribution of mononuclear cells isolated from the bovine mammary gland during the nonlactating (dry) period was examined using monoclonal antibodies against leukocyte cell surface antigens, cellular light scattering properties, and the presence of nonspecific esterase. Most of the mononuclear cells isolated during the dry period were lymphocytes. T cells predominated until about 1 week prior to parturition. During the week prior to calving, the percentage of B cells increased until it approximated T cells. The ratio of CD4:CD8 cells was 2-3:1 for mammary gland T cells. This was similar to the ratio found in peripheral blood. At dry-off, about 12% of mammary mononuclear cells were macrophages. The macrophage percentage increased (to about 30%) at mid-dry and remained at this levels until parturition. PMN's were isolated with the mononuclear cells during the first 2 weeks dry and the week prior to calving. Three methods were used to identify mammary macrophages. Esterase staining (as an enzymatic method), forward angle/90 degrees light scatter (based on size and internal complexity), and MHC class II/forward angle light scatter (based on size and surface markers) were compared. Each method yielded similar specificity for macrophage identification. Non-adherent cell fractions, obtained by passage of the cells over Sephadex G-10 columns, were enriched in CD4 positive T cells, somewhat depleted of B cells, and depleted of macrophages and PMN's. Cells eluted from G-10 columns, with lidocaine, were mostly lymphocytes, but reflected the cells loaded onto the column.

Animals↗
PubMed1990

Dimensional mapping of the active site of cholesterol esterase with alkylboronic acid inhibitors.

The cholesterol esterase-catalyzed hydrolysis of the water-soluble substrate p-nitrophenyl butyrate occurs via an acylenzyme mechanism, and is competitively inhibited by boronic acid transition state analog inhibitors. Accordingly, we undertook to dimensionally map the enzyme's active site via synthesis and characterization of a series of n-alkyl boronic acid inhibitors. The most potent of these is n-hexaneboronic acid, with a Ki = 13 +/- 1 microM, since inhibitor potency declines for both longer and shorter boronic acids. No inhibition is observed for methaneboronic acid and n-octaneboronic acid inhibits poorly, with a Ki of 7 mM. These results indicate that the ability of the enzyme to form tight complexes with boron-containing transition state analog inhibitors is sensitive to alkyl chain length. The trend in inhibitor potency is discussed in terms of substrate specificity of and transition state stabilization by cholesterol esterase, and has important implications for the design of optimal reversible inhibitors of the enzyme.

Alkylation↗
PubMed1989

Influence of the organophosphorus compound DFP on inhibitory motor systems and esterase activity in the spinal cord of cats.

In high spinal cats, the acute time-dependent changes of both the activity of spinal reflex pathways and the activity of three different esterases (acetylcholinesterase, carboxylesterase and neurotoxicant target enzyme) in the spinal cord were investigated after intravenous application of the organophosphorus compound di-isopropyl phosphofluoridate (DFP). There is no general depression of spinal reflexes by DFP. While the recurrent inhibition is completely abolished for a long time and the reflexes to a flexor (PBSt) are depressed but with a shorter recovery time, the reflexes to an extensor (GS) are distinctly less depressed or even facilitated. Reflex pathways from skin afferents to motoneurones did not react in a uniform way to DFP, e.g. inhibitory nociceptive pathways were less affected than excitatory ones. Esterase activities were heavily depressed and recovered with different time courses. The acute DFP action cannot be explained by a uniform intoxication of all spinal functions but probably emerges from a differential action on different interneuronal systems.

Acetylcholinesterase↗
PubMed1989

Isoenzyme patterns of phosphatases and esterases in Fasciola hepatica and Dicrocoelium dendriticum.

A study was made of alkaline and acid phosphatase isoenzymes and non-specific esterases in homogenates of the trematodes Fasciola hepatica and Dicrocoelium dendriticum obtained from infected tissues of Capra hircus and Ovis aries using horizontal polyacrylamide gel electrophoresis. The esterase patterns in F. hepatica and D. dendriticum were different. Homogenate of F. hepatica from both hosts gave four enzyme bands. For D. dendriticum, however, while homogenates of parasites from C. hircus also gave four bands, those of O. aries gave only three bands. Acid and alkaline phosphatases in homogenates of both parasites showed three enzyme bands, but there was a host species difference between the enzyme patterns of specimens collected from C. hircus versus O. aries.

Acid Phosphatase↗
PubMed1995

Specificity of an esterase (XYLD) from Pseudomonas fluorescens subsp. cellulosa.

Activity of an esterase from Pseudomonas fluorescens subsp. cellulosa (XYLD) on an insoluble feruloylated hemicellulose substrate (de-starched wheat bran) was dependent on the source of added endo-xylanase. The esterase exhibited high selectivity for the nature, position of linkage and size of the feruloylated oligosaccharides generated by hydrolysis of the hemicellulose. Increased affinity of XYLD with increasing size of the oligosaccharide substrate suggests that optimal activity is observed on substrates with at least 4 sugars.

Coumaric Acids↗
PubMed1978

Esterase and malate dehydrogenase isozyme polymorphisms in 15 Artemia populations.

1. Starch gel electrophoresis of adult brine shrimps from 15 populations revealed little intrapopulation polymorphism in NAD-dependent malate dehydrogenase (MDH) isozymes or in the two fastest esterases (demonstrated with alpha-naphthyl propionate as substrate). 2. Interpopulation differences could be summarized as three different electrophoresis band patterns for the five- to seven-banded MDH isozymes and another three patterns for the two fastest esterases. 3. These differences in electrophoresis patterns divide the 15 Artemia populations into four categories (each containing one to seven populations) which may be distinguished by isozyme content and which are congruent with categories established by the criterion of reproductive isolation in an earlier study.

Animals↗
PubMed1978

Electrophoretic characterization of the nonspecific esterases of the mosquito, Culex tarsalis: conventional and isoelectric focused acrylamide gels.

1. The nonspecific esterases of the mosquito, Culex tarsalis, were examined through conventional and isoelectric focusing acrylamide gel electrophoresis. 2. Conventional acrylamide gel electrophoresis resolved five components. These were characterized as: three carboxylesterases, one acetylcholinesterase and one acetylesterase. 3. Isoelectric focusing resolved 18 components. These were characterized as: 14 carboxylesterases, two acetylcholinesterases, one acetylesterase and one arylesterase. 4. The reproducibility and reliability of isoelectric focusing is discussed and compared to conventional acrylamide gel electrophoresis for the examination of multi-component isozyme systems such as non-specific esterases.

Animals↗