Showing papers on "Esterase published in 1972"
TL;DR: The theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase is supported.
Abstract: Three mutant strains of Escherichia coli have been isolated which are lacking ferric-enterochelin esterase activity. This enzyme catalyzes the hydrolysis of the enterochelin moiety of ferric-enterochelin to yield ultimately three molecules of N-2,3-dihydroxybenzoylserine. The mutants (designated fes−) were shown to be unaffected in enterochelin biosynthesis, capable of enterochelin-mediated iron uptake, and able to utilize ferric-dihydroxybenzoylserine complexes normally. When grown under iron-deficient conditions, however, they showed an absolute requirement for added iron or citrate, a phenotype characteristic of mutants defective in some part of the enterochelin system of iron uptake. These results support the theory that iron, taken up by the cell as ferric-enterochelin is only available for general cell metabolism after hydrolysis of the ligand by enterochelin esterase. The three fes− strains were shown to be affected in the B component of enterochelin esterase. The fesB gene which is probably the structural gene coding for component B of the esterase, was shown to be located at about minute 14 on the E. coli chromosome together with seven other genes involved in the enterochelin system of iron transport.
179 citations
TL;DR: It is suggested that either the formation or the breakdown of a covalent intermediate through nucleophilic attack on the carbonyl carbon of the substrate is most probably the rate-limiting step in the dehydrogenase reaction scheme.
158 citations
TL;DR: A method was developed for simultaneous detection of proteinase and esterase activity in extremely halophilic bacteria by combining Tween hydrolysis and gelatin hydrolytic activity on a single plate.
Abstract: A method was developed for simultaneous detection of proteinase and esterase activity in extremely halophilic bacteria by combining Tween hydrolysis and gelatin hydrolysis on a single plate.
103 citations
TL;DR: Analysis of albumin which has reacted with p-nitrophenyl acetate indicate that two tyrosyl hydroxyl groups on the protein are rapidly acetylated by the ester.
74 citations
TL;DR: Chicken carbonic anhydrase differs most strikingly from the corresponding mammalian enzymes in its high half-cystine content, and requires the presence of a reducing agent in vitro for maximal enzymatic activity and structural integrity.
65 citations
TL;DR: A soluble enzyme with carbonic anhydrase activity was isolated from pea leaves and purified 200-fold by ammonium sulfate fractionation, gel filtration and preparative polyacrylamide gel electrophoresis, and the amino acid composition of the enzyme has been determined.
50 citations
Journal Article•
TL;DR: The cotton carboxypeptidase hydrolyzes several ester substrates, small polypeptides, and denatured proteins, and yields a single radioactive peptide, indicating that the sequence of amino acids around the active site serine of each subunit is identical.
49 citations
TL;DR: The concept that a whole range of esterase subunits exist, each varying in its capacity to hydrolyze esters of up to an optimal chain length and arranged according to the dictates of specific tissue requirements, is in accord with the present findings.
Abstract: To investigate the nature of esterase polymorphism, nonspecific esterases were investigated in a large number of organs obtained from rat. In starch gel electropherograms the capacity of ester hydrolysis was seen to decline predictably with successively longer chain carbon substrates. An increasing susceptibility to organophosphate inhibition was observed with progressive lengthening of the acyl chain in the substrate molecules. Attempts to hybridize an organophosphate-sensitive esterase with a resistant type yielded a few additional esterase species. Studies on an esterase fraction isolated by column chromatography revealed the highly relative nature of organophosphate inhibition. These suggested that nonspecific esterases all belong to one enzyme system that does not justify the present compartmentation into acetyl-, aryl- or carboxylesterases on grounds of substrate hydrolysis or organophosphate sensitivity. It is likely that esterase species are each built on a subunit structure and exhibit overlappin...
46 citations
TL;DR: It may be suggested that carbon tetrachloride damages the microsomal membrane through lipoperoxidation resulting in phenyl acetate esterase release, which contributes at least in part to the decrease in activity of this enzyme in the liver which occurs 24 to 48 h after Carbon tetrACHloride treatment.
46 citations
TL;DR: Several periphytic marine bacterial cultures were examined for their content of hydrolytic enzymes and quantitative assays were done for extracellular and intracellular proteinase, phosphatase, estera...
Abstract: Several periphytic marine bacterial cultures were examined for their content of hydrolytic enzymes. Quantitative assays were done for extracellular and intracellular proteinase, phosphatase, esterase, β-glucosidase, and four polysaccharide hydrolase activities. While some of the enzymes were released extracellularly by growing cells, the greatest amounts of proteinase, esterase, phosphatase, and β-glucosidase were located in the cells and released by mechanical breakage or by cell autolysis. Substantial amounts of proteinase were found in washed cell envelopes of the bacteria. All of the bacteria showed some enzymatic activity against one or more of the algal and microbial acid polysaccharides tested. Enzymes active against these polyanions were found either extracellularly or in cell extracts, depending on the culture concerned. Partial lysis of cell envelopes from two of the periphytes was produced by extracellular or intracellular enzyme mixtures. The ecological importance of bacterial hydrolases and t...
45 citations
TL;DR: A number of the properties of the active site of IRC-50 arvin, a coagulant enzyme from Agkistrodon rhodostoma, have been studied and evidence is presented which suggests that the esterase and coagulate activity of the enzyme are associated with the same active site.
Abstract: A number of the properties of the active site of IRC-50 arvin, a coagulant enzyme from Agkistrodon rhodostoma, have been studied. The results indicate that the enzyme is in many ways similar to the mammalian serine proteinases.
1
IRC-50 arvin will hydrolyse α-N-benzoyl-L-arginine esters and a study of the rates of hydrolysis of a number of these esters indicates that the hydolysis may proceed via a common acylenzyme intermediate.
2
IRC-50 arvin is inactivated by di-isopropylfluorophosphate and phenylmethanesulphonyl fluoride but at much lower rates than the mammalian serine proteinases.
3
Both the catalytic activity and rate of inactivation of the enzyme by di-isopropylfluorophosphate and phenylmethanesulphonyl fluoride are dependent on the ionisation of a group with pK(app)∼ 7.0; this group is probably a histidine residue.
4
Evidence is presented which suggests that the esterase and coagulant activity of the enzyme are associated with the same active site.
5
Titration of the active site of the enzyme with p′-nitrophenol p′-guanidinobenzoate demonstrates that IRC-50 arvin has one active site per mole, based on a molecular weight of 55000.
TL;DR: It is postulated that particular Chinese hamster esterase genes became inactive after longterm cultivation, and that, in the hybrid cell, a human activator gene linked to the adeB gene and located on a human B-group chromosome reactivated expression of these Chinese ham Sterase genes.
Abstract: Prototrophic hybrids formed from an adenine-requiring Chinese hamster cell and human fibroblasts uniformly display new esterase activity that differs from that of either parental cell in electrophoretic mobility and substrate specificity. The hybrids that grew in the selective medium and possessed the new esterase activity had a single extra chromosome that resembled a B-group human chromosome. When clones of such hybrid cells were cultured in nonselective medium, they rapidly reverted to inability to synthesize adenine, disappearance of the new esterase activity, and simultaneous loss of the extra human chromosome. Esterase activity like that of the hybrid is present in cells of various Chinese hamster, but not human, tissues. It is postulated that particular Chinese hamster esterase genes became inactive after longterm cultivation, and that, in the hybrid cell, a human activator gene linked to the adeB gene and located on a human B-group chromosome reactivated expression of these Chinese hamster esterase genes.
Journal Article•
TL;DR: Soluble-protein and eight enzyme profiles obtained by polyacrylamide-gel electrophoresis were compared between Meloidogyne incognita and M. arenaria to find patterns that varied when nematodes were propagated on different host plants.
Abstract: Soluble-protein and eight enzyme profiles obtained by polyacrylamide-gel electrophoresis were compared between Meloidogyne incognita and M. arenaria. Esterase, malate dehydrogenase, and[alpha]-glycerophosphate dehydrogenase patterns were distinctly characteristic for each species. Peroxidase and[alpha]-glycerophosphate dehydrogenase isoenzyme patterns varied when nematodes were propagated on different host plants. Similar profiles were obtained for two populations within each species. Antigenic proteins of these two species were compared following separation by electrophoresis. Key words: peroxidase, root-knot nematodes, characterization, antigens.
TL;DR: Results are consistent with the hypothesis that under conditions of iron deficiency iron is transported into E. coli cells as ferric enterochelin but that the iron of this complex is unavailable to the cell until the ligand is hydrolyzed by ferric Enterochelin esterase.
TL;DR: A protease produced by Clostridium botulinum type B (strain Lamanna) was isolated and characterized and is active only when in the reduced state and is more stable when Ca 2+ is present.
TL;DR: Yeast proteinase C liberates carboxy-terminal amino acids from a wide variety of N-acyl dipeptides which have aromatic, neutral, acidic or basic amino acid in the car boxy- terminal end.
TL;DR: It is found that protease and esterase activity of human PMN exist in a latent form in a class of membrane-bound particles which sediment at a distinctive density.
Abstract: SummaryWe find that protease and esterase activity of human PMN exist in a latent form in a class of membrane-bound particles which sediment at a distinctive density. Readily separated from these granules by sucrose density gradient centrifugation is a separate class of particles, which is associated with an aminopeptidase not previously described in human PMN lysosomal granules. Protease, esterase, and aminopeptidase act optimally at or near pH 7.2.
TL;DR: BeiRattus norvegicus wird eine neue Mutation beschrieben, welche die elektrophoretische Wanderungsgeschwindigkeit eines Intestinalenzymes beeinflusst.
Abstract: BeiRattus norvegicus wird eine neue Mutation beschrieben, welche die elektrophoretische Wanderungsgeschwindigkeit eines Intestinalenzymes beeinflusst.
Journal Article•
TL;DR: Unpublished observations in the laboratory have confirmed that the enzyme responsible for pilo-carpine hydrolysis is not cholinesterase.
Abstract: Evidence has been presented that the en-zyme, apparently an esterase, is probablycation dependent. Enzyme activity is lostby heating or with the addition of variouschelating agents: EDTA (ethylene dia-minetetraacetate), trien, penicillamine,neomycin sulfate, kanamycin sulfate, andethambutol hydrochloride. Unpublishedobservations in our laboratory have estab-lished that the enzyme responsible for pilo-carpine hydrolysis is not cholinesterase.
TL;DR: Embryos cultured from the two-cell stage or viable blastocysts which have been unable to hatch from their zona pellucidae also produce trophoblast-like esterase, and these profiles closely resemble those of the yolk sac and embryo proper, even after 3 weeks in culture.
TL;DR: It is demonstrated that scission of a bond to the first coordination sphere of the metal is not necessary for the hydrolysis of ester substrates in the case of Co(III) carboxypeptidase A.
TL;DR: Comparison of these enzymes with human δ-chymotrypsin indicates a high degree of similarity in both amino acid composition and in the method of activation, but differences in specific esterase activity would suggest that each of the three enzymes was derived from a separate, distinct zymogen.
TL;DR: The ontogeny of esterase and cholinesterase isozymes in normally developing, animalized, and radialized sea urchin embryos was studied using the technique of disc electrophoresis on polyacrylamide gels.
TL;DR: Observations suggest that substrate activation is solely a manifestation of the structure of the enzyme protein, indicating that substrateactivation is species dependent.
TL;DR: Studies of the enzymatic properties show that the enzyme is a very efficient catalyst in the CO2 hydration reaction and has a weak esterase function towards p-nitrophenyl acetate, which resembles the highly active forms of the mammalian carbonic anhydrases.