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At least 19 recordsLinked to original sources
PubMed1976

Immobilization of a cephalosporin acetylesterase by containment within an ultrafiltration device.

A cephalosporin acetylesterase produced by Bacillus subtilis catalyzes the deacetylation of 7-aminocephalosporanic acid (7-ACA). Previous reports from our laboratory described the kinetic constants that characterize the reaction: Km = 2.8 X 10(-3)M, Kia acetate = 5 X 10(-2)M, and Kid deacetyl-7-ACA = 3.6 X 10(-2)M. These constants were used to predict the time course of the reaction using the following equation for dual competitive product inhibition. (see article) where St =mg/ml 7-ACA, At =mg/ml acetate, Dt =mg/ml deacetyl-7-ACA. The predicted time course closely matched the time course measured experimentally. The equation also was solved without the inhibition terms and the solution indicated that product inhibition caused about a 30% increase in the time required for complete (greater than 97%) hydrolysis of a 24 mg/ml 7-ACA solution. The esterase was immobilized by containment within an ultrafiltration device. With this technique the enzyme was reused 20 times over an 11 day span to deacetylate 7-ACA solutions containing 4 to 24 mg/ml 7-ACA. The specific activity after the 20th use was the same as the activity prior to the first use, indicating little enzyme inactiviation occurred.

Acetylesterase↗
PubMed1978

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.

Acetylesterase↗
PubMed1975

Preparation and properties of a cephalosporin acetylesterase adsorbed onto bentonite.

A cephalosporin acetylesterase produced by Bacillus subtilis was immobilized by adsorption onto bentonite. The immobilized enzyme (E(I)) and the soluble enzyme (E(S)) exhibited Michaelis-Menton kinetics with 7-aminocephalosporanic acid (7-ACA): K(m) = 2.8 x 10(-3) M and K(m) = 3.2 x 10(-3) M, respectively. Similar kinetics were observed with 7-(thiophene-2-acetamido)cephalosporanic acid (cephalothin), but the K(m) value measured with E(I) (3.7 x 10(-3) M) was less than one-half that measured with this substrate and E(S). The reduction in K(m) value was correlated with the ability of bentonite to adsorb cephalothin. The reaction products, acetate and deacetyl-7-ACA, were weak competitive inhibitors of E(S) and E(I). The K(i) values for E(I) were 5.0 x 10(-2) M for acetate and 3.6 x 10(-2) M for deacetyl-7-ACA. Similar values were measured with E(S) and these substrates. E(I) retained about 80% of its initial activity after 3 weeks of storage in solution at 25 C. However, the enzyme dissociated from the bentonite particles during the deacetylation reaction. This dissociation was minimized by cross-linking E(I) with glutaraldehyde or bis-dimethyladipimidate, or by adding Al(OH)(3) to the suspension. With the latter addition, E(I) was stabilized so that it could be reused nine times before one-half of the initial activity was lost.

Acetylesterase↗
PubMed1975

Physical properties and kinetic behavior of a cephalosporin acetylesterase produced by Bacillus subtilis.

An esterase that deacetylates cephalosporins was recovered from the supernatant of a Bacillus subtilis culture. It was partially purified by ammonium sulfate fractionation and ultrafiltration. The enzyme had a temperature optimum between 40 and 50 C and a pH optimum of 7.0. The molecular weight was estimated by gel filtration to be 190,000. The enzyme was very stable and retained greater than 80% of its activity after storage in solution at 25 C for 1 month. The esterase exhibited Michaelis-Menton kinetics with the substrates 7-aminocephalosporanic acid (7-ACA) and 7-(thiophene-2-acetamido)cephalosporanic acid (cephalothin); the K(m) values were 2.8 X 10(-3) and 8.3 X 10(-3) M, respectively. The products of 7-ACA deacetylation were weak competitive inhibitors, and a K(i) value of 5.0 X 10(-2) M was determined for acetate and of 3.6 X 10-2 M for deacetyl-7-ACA. Weak product inhibition did not prevent the deacetylation reaction from going to completion. A 5-mg/ml solution of partially purified esterase completely hydrolyzed (greater than 99.5%) a 24-mg/ml solution of 7-ACA in 3 h. Because of the kinetic properties and excellent stability, this enzyme may be useful in an immobilized form to prepare large quantities of deacetylated cephalosporin derivatives.

Acetylesterase↗
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↗
PubMed1978

Non-specific acid esterase activity in rat lymphocytes.

In a first night's collection of rat thoracic duct lymphocytes B- and T-cells were distinguished on cytocentrifuge smears by complementary markers: B-cells by rosette-formation with Staphylococcus aureus Strain Cowan 1 armed with rabbit antiserum to rat F(ab')2 and T-cells by high uptake of 3H-uridine demonstrated by autoradiography. On incubation of the cytocentrifuge smears for demonstration of alpha-naphthyl-acetate esterase (ANAE)-activity, most B-cells showed large, intense colour deposits often located in the uropod. T-cell ANAE-activity on the other hand was variable, possibly due to variations in experimental conditions. When present, the T-cell colour deposits were small, dot-like and of low intensity. ANAE-activity may then be used to differentiate between rat T- and B-cells, being a marker for the latter cell type. This is unexpected as others have reported that ANAE-activity is specific for T-cells in mouse and man. Studies with inhibitors indicate that the rat B-cell enzyme belongs to the acetylesterases.

Acetates↗
PubMed1977

Isoenzyme status and genetic variability of serum esterases in the lesser snow goose, Anser caerulescens caerulescens.

A maximum of 22 bands comprising four esterase subgroups--acetylesterase, carboxylesterase, cholinesterase, and acetylcholinesterase--were detected following electrophoresis of lesser snow goose sera on polyacrylamide gels. A minimum of seven structural genes was surmised to be involved in the biosynthesis of these enzymes following physiochemical characterizations. The genetic variability of these loci was calculated to be 1.25% average heterozygosity, while 14.3% of the loci were polymorphic. These estimates of genetic variability were substantially lower than those reported for other vertebrate species. The low degree of genetic variability found in snow goose serum esterases coupled with the extensive protein multiplicity observed may possibly reflect an adaptive strategy based on "biochemical plasticity" rather than genic heterozygosity for this species. The nature of evolutionary forces acting upon multiple enzyme systems such as esterases is discussed. The concept of "conditional neutrality" is introduced and defined within this context.

Animals↗
PubMed1978

Electrophoretic separation of esterases of Alaria marcianae (La Rue, 1917) (Trematoda).

1. Disc electrophoresis was used to determine the esterase isoenzymes present in adults of the strigeoid trematode Alaria marcianae (La Rue, 1917). 2. Eight esterase bands were found with alpha-naphthyl acetate as the substrate and Fast Blue RR as the dye. 3. From results obtained with inhibitors, four different types of esterases were tentatively identified; cholinesterase (one band), ali-esterase or B-type (one band), arylesterase or A-type (2 bands) and acetylesterase or C-type (4 bands).

Animals↗
PubMedDate not supplied

[Lysosomal component in the mechanism of the toxic effect of sporofusarin].

The effect of Fusarium sporotrichiella v. sporotrichioides mycotoxin (sporofusarin) on the total and non-sedimentary supernatant activity of 13 marker-enzymes of subcellular particles (2 mitochondrial enzymes-cytochrome oxidase and malate dehydrogenase; 8 lysosomal enzymes -- acid phosphatase, acid RNAase, acid DNAase, arylsulphatases A and B, beta-N-acetylglucosaminidase, beta-glucuronidase, beta-galactosidase and beta-glucosidase; 2 microsomal enzymes -- glucose-6-phosphatase and acetylesterase; plasma membrane enzyme -- alkaline phosphatase) of the rat liver, kidney, spleen and bone-marrow was studied in in vivo experiments. The latter demonstrated that sporofusarin effects were characterized by a significant organ and organella specificity, viz. the toxin caused a sharply increased activity, mainly of lysosomes enzymes and labilization of the lysosomal membranes, primarily in the spleen and the bone-marrow. A conclusion is drawn that the discovered selective destructive action of sporofusarin on the lysosomes may be regarded as a new phenomenon that, possibly is directly related to the characterization of the mechanism responsible for a specific effect produced by sporofusarin.

Animals↗
PubMed1976

A mutation affecting expression of the gene coding for serine transacetylase in Salmonella typhimurium.

A 1,2,4-triazole resistant mutant of S. typhimurium has been isolated, in which serine transacetylase activity is seven times higher than in wild type. Partially purified serine transacetylase from a strain carrying the trz-312 mutation has kinetic properties which are virtually identical to those of the wild type enzyme and binds to O-acetylserine sulfhydrylase A to form a cysteine synthetase complex which is also indistinguishable from that found in wild type. Thus the increased activity of serine transacetylase associated with trz-312 appears to result from increased quantities of a kinetically normal, enzyme protein. Resistance to 1,2,4-triazole is probably due to the ability of trz-312 strains to synthesize O-acetyl-L-serine at a rapid enough rate to compensate for that utilized by the O-acetylserine triazolylase reaction. Genetic mapping experiments, using P1-mediated transduction, show that trz-312 is 91-99% linked to cysE, the structural gene for serine transacetylase. The results of three point crosses indicate that this mutation is located at one extreme end of the cysE locus, as would be expected for a promotor mutation.

Acetylesterase↗
PubMed1978

Sodium butyrate inhibits histone deacetylation in cultured cells.

Sodium butyrate in millimolar concentrations causes an accumulation of acetylated histone species in a variety of vertebrate cell lines. In all lines tested, butyrate caused hyperacetylation of H3 and H4, and in rat IRC8 cells, H2A and H2B were also affected. In Friend erythroleukemic cells, butyrate also induces the synthesis of a nonhistone chromosomal protein, IP25. butyrate does not affect the rate of histone acetylation in cell-free extracts of nuclei of Friend cells. Rather, this fatty acid inhibits histone deacetylation. Cell-free extracts of either control cells or butyrate-grown cells contain comparable levels of histone-deacetylating activity. This in vitro activity is inhibited by the addition of butyrate to the extracts. Thus butyrate appears to be an inhibitor of histone deacetylases both in vivo and in vitro.

Acetylation↗