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Esterase
About: Esterase is a research topic. Over the lifetime, 7622 publications have been published within this topic receiving 168270 citations.
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TL;DR: The electric organ of Torpedo, which is considered as an accumulation of muscle end plates, has by far the highest content of choline esterase ever found in a tissue of fluid.
Abstract: THE physiological significance of choline esterase suggested by its high concentration at muscle end plates and at synapses of the central nervous system1 makes it desirable to investigate the properties of the enzyme. The electric organ of Torpedo, which is considered as an accumulation of muscle end plates, has by far the highest content of choline esterase ever found in a tissue of fluid. An organ of 100–200 gm. weight splits about 200–400 gm. acetyl-choline in 60 min., which is a hydrolytic power of the same order of magnitude as calculated for end plates. The organ has therefore been used as material for the preparation of active enzyme solutions2.
60 citations
TL;DR: The toxic effects of the final degradation products were investigated, using various recombinant bioluminescent bacteria and, as a result, the degradation products from yeast esterase were shown to contain a toxic hazard, causing oxidative stress and damage to protein synthesis.
Abstract: The efficiency of two lypolytic enzymes (fungal cutinase, yeast esterase) in the degradation of di-(2-ethylhexyl)-phthalate (DEHP) was investigated. The DEHP-degradation rate of fungal cutinase was surprisingly high, i.e. almost 70% of the initial DEHP (500 mg/l) was decomposed within 2.5 h and nearly 50% of the degraded DEHP disappeared within the initial 15 min. With the yeast esterase, despite the same concentration, more than 85% of the DEHP remained even after 3 days of treatment. During the enzymatic degradation of DEHP, several DEHP-derived compounds were detected and time-course changes in composition were also monitored. During degradation with fungal cutinase, most DEHP was converted into 1,3-isobenzofurandione (IBF) by diester hydrolysis. In the degradation by yeast esterase, two organic chemicals were produced from DEHP: IBF and an unidentified compound (X). The final chemical composition after 3 days was significantly dependent on the enzyme used. Fungal cutinase produced IBF as a major degradation compound. However, in the DEHP degradation by yeast esterase, compound X was produced in abundance in addition to IBF. The toxic effects of the final degradation products were investigated, using various recombinant bioluminescent bacteria and, as a result, the degradation products from yeast esterase were shown to contain a toxic hazard, causing oxidative stress and damage to protein synthesis.
60 citations
60 citations
TL;DR: The sequence analysis and the biochemical investigations show that the esterase belongs to the haloperoxidase family, and possessed a typical feature of serine-hydrolases, namely the consensus motif Gly-X-Ser- X-Gly around the active serine of the catalytic triad.
Abstract: SUMMARY: Screening GenBank indicated that an esterase from Pseudomonas fluorescens had high sequence similarity with bacterial non-haem haloperoxides. However, this homology was limited to two distinct domains of the published esterase sequence. As errors in the published sequence were suspected, the esterase gene was sequenced again. The revised sequence displayed between 40 and 50% identical amino acids with the haloperoxidases, but distributed along the whole sequence. In addition to the structural homologies with haloperoxidases, the esterase also displayed functional homology. The recombinant esterase, purified from Escherichia coli cells, was capable of both ester hydrolysis and halogenation, as detected in situ by the formation of bromophenol blue or spectrophotometrically by the bromination of monochlorodimedon. The esterase is thus a bifunctional enzyme. The sequence analysis and the biochemical investigations show that the esterase belongs to the haloperoxidase family. It also possessed, however, a typical feature of serine-hydrolases, namely the consensus motif Gly-X-Ser-X-Gly around the active serine of the catalytic triad. By alignment of the esterase with different serine-hydrolase sequences, it was possible to identify the other two residues of the triad. The triad comprised the residues Ser95, Asp223 and His252. Interestingly, a structurally equivalent catalytic triad was also identified in the sequences of all bacterial non-haem haloperoxidases, in highly conserved domains. The presence of a catalytic triad in haloperoxidases is expected to be important in the mechanism of halogenation.
60 citations
TL;DR: The thermostable esterase from the moderate thermophile Bacillus circulans was purified to homogeneity using a four-step procedure and showed a marked specificity for mid-chain-length fatty acids (3–8 carbon atoms), which classified the enzyme as a carboxylesterase.
Abstract: The thermostable esterase from the moderate thermophile Bacillus circulans was purified to homogeneity using a four-step procedure. Esterase activity was associated with a protein of molecular mass 95 kDa, composed of three identical subunits of 30 kDa. The esterase activity was thermostable with a maximum activity at 55 °C using initial rate assay. The half-inactivation temperature was 71 °C after a 1-h treatment, which compared favorably to that of other enzymes. Activity at temperatures of 30–37 °C was high (about half of maximum), making this new enzyme very attractive for applications in this moderate temperature range. The esterase also showed high activity at a rather alkaline pH (higher than 10). The specificity pattern showed a marked specificity for mid-chain-length fatty acids (3–8 carbon atoms), which classified the enzyme as a carboxylesterase.
60 citations