Acetylesterase Activity Research Articles

The E3 protein of bovine coronavirus is a receptor-destroying enzyme with acetylesterase activity.

In addition to members of the Orthomyxoviridae and Paramyxoviridae, several coronaviruses have been shown to possess receptor-destroying activities. Purified bovine coronavirus (BCV) preparations have an esterase activity which inactivates O-acetylsialic acid-containing receptors on erythrocytes. Diisopropyl fluorophosphate (DFP) completely inhibits this receptor-destroying activity of BCV, suggesting that the viral enzyme is a serine esterase. Treatment of purified BCV with [3H]DFP and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the proteins revealed that the E3 protein was specifically phosphorylated. This finding suggests that the esterase/receptor-destroying activity of BCV is associated with the E3 protein. Furthermore, treatment of BCV with DFP dramatically reduced its infectivity in a plaque assay. It is assumed that the esterase activity of BCV is required in an early step of virus replication, possibly during virus entry or uncoating.

Xylanolytic enzyme activities produced by mesophilic and thermophilic actinomycetes grown on graminaceous xylan and lignocellulose

Mesophilic and thermophilic strains of actinomycetes were grown on media containing graminaceous xylan or lignocellulose. Aliquots of the culture fluids were sampled and assayed for enzyme activities involved in the degradation of hemicellulose. Xylanase, acetyl esterase and α-arabinofuranosidase activities could be detected after different times of incubation; their production was also dependent on the growth medium. The highest levels of xylanase activity were found in cultures of strains of Streptomyces, Actinomadura sp. and Saccharomonospora viridis. Streptomyces cyaneus produced the highest amount of arabinofuranosidase whereas acetyl esterase activities were highest in S. cyaneus, S. viridis and Pseudonocardia thermophila.

Human and bovine coronaviruses recognize sialic acid-containing receptors similar to those of influenza C viruses.

Human coronavirus OC43 and bovine coronavirus elute from agglutinated chicken erythrocytes when incubated at 37 degrees C, suggesting the presence of a receptor-destroying enzyme. Moreover, bovine coronavirus exhibits an acetylesterase activity in vitro using bovine submaxillary mucin as substrate similar to the enzymatic activity found in influenza C viruses. Furthermore, pretreatment of erythrocytes with either influenza C virus or bovine coronavirus eliminates subsequent binding and agglutination by either coronaviruses or influenza C virus, whereas binding of influenza A virus remains intact. In addition, hemagglutination by coronaviruses can be inhibited by pretreatment of erythrocytes with Arthrobacter ureafaciens or Clostridium perfringens neuraminidase or by addition of sialic acid-containing gangliosides. These results suggest that, like influenza C viruses, human coronavirus OC43 and bovine coronavirus recognize O-acetylated sialic acid or a similar derivative as cell receptor.

The glycoprotein of influenza C virus is the haemagglutinin, esterase and fusion factor.

Of the biological activities of influenza C virus, haemagglutination, receptor inactivation and fusion, only the latter has been conclusively correlated with its surface glycoprotein (gp). We have purified the gp by octylglucoside treatment of influenza C virions followed by centrifugation into a sucrose gradient. Evidence was obtained that gp also represents the receptor-destroying enzyme of influenza C virus, which has been characterized as a neuraminate 9-O-acetylesterase: (i) it inactivated the receptors for influenza C virus on chicken erythrocytes; (ii) it had acetylesterase activity as indicated by the release of acetate from bovine submandibulary mucin; (iii) monoclonal antibodies directed against gp inhibited the acetylesterase activity of influenza C virus. Although purified gp was unable to agglutinate chicken red blood cells, it blocked haemagglutination by viruses. This finding as well as the haemagglutination inhibition activity of monoclonal anti-gp antibodies indicate that gp is also responsible for the haemagglutinating activity of influenza C virus. Thus, as the influenza C glycoprotein is the only myxovirus glycoprotein with three different activities, we propose the designation HEF in order to describe its function as a haemagglutinin (H), an esterase (E) and a fusion factor (F).

Activation of carboxylesterases in root cortical parenchymal cells of Pisum sativum during xylem induction in vitro.

A quantitative cytochemical study of naphthol AS-D esterase activity in explants from roots of Pisum sativum grown on basal medium for 3 or 6 days showed similar levels of activity to those seen in sections of cortex and stele from intact roots of similar ages. Explants grown in the presence of auxins or cytokinin alone showed a threefold or twofold increase in cortical parenchymal activity, respectively. On adding both hormones to initiate xylem element formation, there was also a threefold increase in activity in the cortex. In all three cases, the stimulated activity was totally inhibited by either 10(-4) M diisopropylfluorophosphate (DFP) or 10(-4) M diethyl p-nitrophenylphosphate (E600), indicating carboxylesterase activity. The low level of activity normally present in cortical cells was inhibitor resistant, so indicating acetylesterase activity. Thus, auxins and cytokinins appear to activate mainly similar carboxylesterases during the initiation of xylem elements from cortical parenchyma cells.

Acetylesterase in lymphoblastic leukaemia associated with thymic enlargement.

Focal cytoplasmic acetylesterase activity was sought in the malignant cells of 91 consecutive children with acute lymphoblastic leukaemia, of whom 10 had an anterior mediatstinal mass at diagnosis. This subgroup with thymic disease (TD) was characterized by hyperleucocytosis, the total leucocyte count being greater than 200 X 10(9)/1 in 6 patients. Furthermore, there was a significant association (P less than 0.025) between TD and the presence of leukaemic blast cells expressing a thymic phenotype, in the form of rosette formation with sheep erythrocytes. Focal cytoplasmic acetylesterase activity identified TD with a sensitivity of 20%, a specificity of 91%, a positive predictive value of 25%, a negative predictive value of 88% and a diagnostic accuracy of 81%. The demonstration of this feature by a simple cytochemical technique can be a useful component of the profile of investigations which are employed in the classification of acute lymphoblastic leukaemia.

Cephalosporin acetylesterase activity of Fusaria

Cephalosporin acetylesterase activity was detected in a number of fusaria tested. Of these Fusarium oxysporum AY F-298 was found to be the most active. Deacetyl derivatives of cephalothin and phenoxymethyl cephalosporin prepared by hydrolysis of the parent compounds with AY F-298 showed low antimicrobial activity.

Acetylesterase isoenzymes in rat uterus and placenta.

The occurrence of acetylesterase activity in the uterus and placenta of the rat has been investigated using a general histochemical simultaneous coupling technique after separation on polyacrylamide gradient gels. apart from a complex band associated with serum esterases which was demonstrated in all the tissues studied, several other isoenzyme bands were demonstrable in differing degrees in the yolk sac and the virgin uterus. Two of these bands were evident in metrial gland up to day 16 of pregnancy, and a third became present by day 17. Unlike the other two bands, this new band did not seem to be associated with the large granules of the granulated metrial gland cells. None of these bands were detected in trophoblast. The metrial gland isoenzymes reacted as well at acid pH as at neutral pH. The yolk sac isoenzymes reacted either as well or slightly better at acid pH, and one extra band was demonstrable under acid conditions.

Multiple forms of acetyl-naphthyl-esterase activity in soil organic matter

Acetyl-naphthyl-esterase activity has been identified and characterized in organic matter extracted from an A 1 horizon of an Alpine podzol. The temperature optimum of the esterase is about 75° C and its activity rises with increasing pH, without reaching a maximum value in the tested range. The Michaelis constant has been determined as Km = 2.950 mM. Pronase does not disrupt esterase activity. Electrofocusing in acrylamide gel shows several peaks of enzyme activity, which correspond with humic isoelectric bands. The location of acetyl-esterase activity in organic matter is discussed.

Microsomal acetylesterase activity in tumor-bearing rats.

Microsomal acetylesterase activity in tumor-bearing rats.

A comparative analysis of the tissue esterases of the white crappie ( Pomoxis annularis rafinesque) and black crappie ( Pomoxis nigromamaculatus lesueur) by electrophoresis and selective inhibitors

1. 1. The multiple forms of soluble esterases were compared for the brain, liver and skeletal muscle of the white and black crappie. 2. 2. The two species exhibited a high tissue specific gene function. 3. 3. No soluble cholinesterase activity was found; however, carboxylesterase, arylesterase and acetylesterase activity was present. 4. 4. The esterases of the brain and liver were similar between species in terms of multiplicity, substrate utilization and inhibitor sensitivity. However, the skeletal muscle of the white crappie contained esterase bands inhibited by p-HMB (arylesterase) whereas the black crappie did not. 5. 5. The inhibitory properties of fourteen organophosphate and carbamate compounds were compared for the esterases of the two species.

Regional distribution of isozymes of D-amino-acid oxidase and acetylesterase in developing primate brain

Isozymes of d-amino-acid oxidase and acetylesterase in different regions of the brain of the developing rhesus monkey were separated by starch gel electrophoresis. Activity of d-amino-acid oxidase was identified by the use of d-phenylalanine as substrate in a coupled peroxidase system, and acetylesterase activity was identified by using alpha-naphthyl acetate as substrate in the presence of Diazo Blue. d-amino-acid oxidase isozymes in the brain of the juvenile (2- to 3-year-old) monkey were localized primarily in brain stem, cord, and midline and lateral cerebellum but were also demonstrable in zymograms of subcortical white matter, corpus callosum, thalamus, hypothalamus, pituitary gland, and globus pallidus. Although isozymes of acetylesterase were more generally distributed throughout all brain areas, one band (band 1) was much more prominent in specimens from caudate nucleus and putamen than in specimens from any other area of brain. Isozymes of d-amino-acid oxidase were not generally detected until after birth, but then all major bands appeared fairly rapidly. By 20 weeks of postnatal age patterns of zymograms were similar to those of the adult brain. Although zymograms of the isozymes of acetylesterase in the brain of the first trimester fetus were very similar to those in regions of brain of the 2- to 3-year-old animal, one band (band 6) was much more pronounced in the zymograms of fetal brain than in those from brains at any later age. The principal contribution of these studies is the demonstration of ( a) an enormously higher concentration, relative to other brain regions, of one of the acetylesterase isozymes (band 1) in extracts of caudate nucleus and putamen, ( b) the progressive decline of one of the acetylesterase isozymes (band 6) during fetal development, and ( c) the occurrence of two different patterns of distribution and development of isozymes in the primate central nervous system.

Isolation und Charakterisierung von Sphärosomen und Glyoxisomen aus Tabakendosperm

1. Sphaerosomes (oil droplets) extracted and isolated from tobacco endosperm contain over 90% of the total endosperm lipids. About 99% of the dry matter of these organelles consist of reserve lipids. 2. Upon germination 90% of the lipid reserves are mobilized within 96 hours. The hydrolysis of the neutral fat is achieved by lipolytic activity present in sphaerosomes. This activity could be demonstrated in sphaerosomes of resting seeds. 3. A large fraction of the total activities of proteases, acetyl esterase, phosphatase, RNase and DNase present in the endosperm extract is localized in sphaerosomes. These enzyme activities are present in resting seeds. Protease, acetyl esterase and phosphatase activities increase temporarily in the course of germination. 4. The sphaerosomes of tobacco endosperm are interpreted as lysosomes in which not only the accumulation and mobilization of the reserve lipids take place, but also the breakdown of autophagocytized cytoplasmic material. The morphological and functional relations between sphaerosomes and other types of vacuoles are discussed. 5. Enzymes of the glyoxylic acid cycle present in the endosperm extract from germinating seeds can be sedimented together with mitochondrial enzymes. Upon centrifugation of the mitochondrial fraction in density gradients of sucrose mitochondria can be separated from glyoxisomes. 6. In addition to isocitrate lyase and malate synthetase catalase is associated with glyoxisomes. The former enzymes are present almost exclusively in the fraction of glyoxisomes whereas about 90% of the latter occur in the soluble fraction. 7. The function of glyoxisomes in the conversion of fatty acids into sugar is discussed.

Direct measurement of acetylesterase in living protist cells.

The fluorogenic acetylesterase (acetic ester hydrolase EC 3.1.1.6.) substrate, fluorescein diacetate, was used to measure enzyme activity in living protist cells. The visual enzyme assay was done by monitoring fluorochromasia by fluorescent microscopy. Quantitative fluorogenic assays were done by measuring the evolved fluorescein in a fluorometer. Of 59 strains of bacteria, 35 were fluorochromatically positive. Eight of the fluorochromatically negative strains were fluorogenically positive. Of 22 strains of slime molds and fungi, all were fluorochromatically positive. Three out of 12 different algae were fluorochromatically positive. Several unidentified protozoa were also fluorochromatically positive. Four out of six protozoa were fluorochromatically positive. Structures of special interest showing acetylesterase activity were: the growing hyphal tips of fungi, the vacuolated areas of yeast and protozoa, newly formed bacterial spores or immature fungal spores, "mesosome-like" bodies in Bacillus megaterium, and the cell membrane and nuclear region of green algae. Yeast protoplasts and bacterial protoplasts and spheroplasts were fluorochromatically positive when derived from positive cells and negative when derived from negative cells. There was no correlation between the possession of a capsule and acetylesterase activity. There was no effect on the viability of bacterial cells incubated in the presence of fluorescein diacetate. Paraoxon inhibited bacterial and yeast enzyme at 10(-5)m. Eserine (10(-5)m) and Paraoxon (10(-7)m) inhibited B. megaterium enzyme. Sodium acetate at 10(-2)m did not inhibit bacterial enzyme. The implications of these findings on the location and expression of esterase activity in living cells are discussed.

Isolation und Charakterisierung von Sph�rosomen und Glyoxisomen aus Tabakendosperm

1. Sphaerosomes (oil droplets) extracted and isolated from tobacco endosperm contain over 90% of the total endosperm lipids. About 99% of the dry matter of these organelles consist of reserve lipids. 2. Upon germination 90% of the lipid reserves are mobilized within 96 hours. The hydrolysis of the neutral fat is achieved by lipolytic activity present in sphaerosomes. This activity could be demonstrated in sphaerosomes of resting seeds. 3. A large fraction of the total activities of proteases, acetyl esterase, phosphatase, RNase and DNase present in the endosperm extract is localized in sphaerosomes. These enzyme activities are present in resting seeds. Protease, acetyl esterase and phosphatase activities increase temporarily in the course of germination. 4. The sphaerosomes of tobacco endosperm are interpreted as lysosomes in which not only the accumulation and mobilization of the reserve lipids take place, but also the breakdown of autophagocytized cytoplasmic material. The morphological and functional relations between sphaerosomes and other types of vacuoles are discussed. 5. Enzymes of the glyoxylic acid cycle present in the endosperm extract from germinating seeds can be sedimented together with mitochondrial enzymes. Upon centrifugation of the mitochondrial fraction in density gradients of sucrose mitochondria can be separated from glyoxisomes. 6. In addition to isocitrate lyase and malate synthetase catalase is associated with glyoxisomes. The former enzymes are present almost exclusively in the fraction of glyoxisomes whereas about 90% of the latter occur in the soluble fraction. 7. The function of glyoxisomes in the conversion of fatty acids into sugar is discussed.

Lipase and acetyl esterase activities in intact Bacillus coagulans spores.

Since data on esterase content of intact dormant spores are meager, a study was carried out with various enzyme substrates and several methods of product detection on intact and ruptured preparations of Bacillus coagulans. Measurement of hydrolysis of triacetin, naphthyl acetates, fluorescein diacetate, ethyl acetate, and ethyl butyrate demonstrated the presence of arylesterase, carboxylesterase, acetyl esterase, and lipase activities in both the intact and ruptured preparations of the non-germinated organism used. It was observed that spore esterase was inhibited by normal and basic copper acetate, eserine, taurocholate, 253.7 mμ ultraviolet light, and temperatures between 50 and 100 °C.

Properties and classification of the soluble esterases of human brain.

Water-soluble proteins and enzymes of human brain were separated by vertical zone electrophoresis in starch gel. Fifteen bands of esterase activity were detected in brain. Various substrates and inhibitors were used in efforts to identify enzymes in addition to a comparison of the esterase pattern with patterns obtained from other human tissues. One zone, composed of four bands of acetylesterase activity, was found to be common to all the tissues investigated with the exception of serum. Two bands of cholinesterase and two bands of A-esterase activity were identified. The remaining bands, which were aliesterases possessing broad overlapping substrate specificity and inhibitor sensitivity, were electrophoretically different from those of other tissues. Observations on alkaline phosphatase, acid phosphatase, and lactate dehydrogenase were recorded for comparison with the data on esterases.

The postulated acetyl esterase activity of streptokinase

The postulated acetyl esterase activity of streptokinase