Topic
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 red yeast Rhodotorula mucilaginosa produced an esterase that accumulated in the culture supernatant on induction with triacetin that was specific for substrates bearing an O-acetyl group, but was relatively nonspecific for the rest of the molecule.
Abstract: The red yeast Rhodotorula mucilaginosa produced an esterase that accumulated in the culture supernatant on induction with triacetin. The enzyme was specific for substrates bearing an O-acetyl group, but was relatively nonspecific for the rest of the molecule, which could consist of a phenol, a monosaccharide, a polysaccharide, or an aliphatic alcohol. The esterase was more active against acetylxylan and glucose β-d-pentaacetate than were a number of esterases from plant and animal sources, when activities on 4-nitrophenyl acetate were compared. The enzyme exhibited Michaelis-Menten kinetics and was active over a broad pH range (5.5 to 9.2), with an optimum between pH 8 and 10. In addition, the enzyme retained its activity for 2 h at 55°C. The yeast that produced the enzyme did not produce xylanase and, hence, is of interest for the production of acetylxylan esterase that is free of xylanolytic activity.
64 citations
TL;DR: An enzymatic inhibition method sufficiently sensitive and reproducible for detecting ten organophosphorus pesticides and carbaryl resolved by thin-layer chromatography is described, with results satisfactory with 1-naphthyl acetate as substrate, and with bovine and sheep sera as sources of esterase.
Abstract: An enzymatic inhibition method sufficiently sensitive and reproducible for detecting ten organophosphorus pesticides and carbaryl resolved by thin-layer chromatography is described. Reproducible detection of nanogram amounts of these pesticides is achieved with a 450-µ thick gel layer, steer-liver homogenate as source of esterase, and indoxyl or substituted indoxyl acetates (5-bromoindoxyl, 5-bromo-4-chloroindoxyl and 5-bromo-6-chloroindoxyl acetates) as substrates, the esterase and substrate spray solutions being used at a pH of about 8. The coloured products of enzymatic hydrolysis of these substrates are stable and intense; white spots indicated the sites of pesticides that inhibited the enzyme.Spots persist for days when the amounts present are 1 ng of parathion; 2ng of carbophenothion; 5ng of azinphos-methyl, diazinon, ethion, malathion and parathion-methyl; 20 ng of carbaryl, Trithion®-methyl and mevinphos; and 100ng of disulfoton. Carbophenothion and disulfoton are also detected at the 1 ng level and carbaryl, at 5 ng; however, the spots produced disappear within a few hours.Unsatisfactory results are obtained with 1-naphthyl acetate as substrate, and with bovine and sheep sera as sources of esterase.
64 citations
TL;DR: Cutinase from V. inaequalis belongs to the class high content of glycine, ahigh content of nonpolar amino acids, two of serine hydrolases, a characterisitic shared with other fungal cutinases, and a high degree of hydrophobicity.
Abstract: K61ler, W., and Parker, D. M. 1989. Purification and characterization of cutinase from Venturia inaequalis. Phytopathology 79:278-283. Venturia inaequalis was grown in a culture medium containing purified cutinase from V. inaequalis is optimal at a pH of 6 and thus different from apple cutin as the sole carbon source. After 8 wk of growth an esterase was the alkaline pH-optimum reported for other purified cutinases. The isolated from the culture fluid and purified to apparent homogeneity. The hydrolysis of the model esterp-nitrophenyl butyrate was less affected by the enzyme hydrolyzed tritiated cutin and thus was identified as cutinase. The pH. The esterase activity was strongly inhibited by diisopropyl purified cutinase is a glycoprotein with a molecular mass of 21-23 kg/ mol, fluorophosphate, and the phosphorylation of one serine was sufficient for as determined by various procedures. Remarkable structural features are a complete inhibition. Thus, cutinase from V. inaequalis belongs to the class high content of glycine, a high content of nonpolar amino acids, two of serine hydrolases, a characterisitic shared with other fungal cutinases. disulfide bridges, and a high degree of hydrophobicity. Cutin hydrolysis by
64 citations
TL;DR: The exposed nature of the catalytic triad suggests that AXEII is a pure esterase,i.e. an α/β hydrolase with specificity for nonlipidic polar substrates.
64 citations
TL;DR: The oligotrophic biofilm was found to contain about twice as much extracellular esterase activity as the more eutrophic River Clywedog biofilm, although these activities also fluctuated during the colonization period.
Abstract: SUMMARY. 1. Extracellular hydrolytic enzyme activities and cell densities were monitored during undisrupted biofilm formation on pristine surfaces in two contrasting river sites in North Wales: an oligotrophic mountain stream (Nant Waen) and a mildly eutrophic river (River Clywedog).
2. Bacterial densities generally increased at both sites over a 33-day monitoring period. Densities in the eutrophic site were approximately 14 times greater than in the mountain stream.
3. Using fluorescent substrate analogues, biofilms from Nant Waen produced low, variable xylosidase and β-glucosidase activities. Biofilms from the more eutrophic River Clywedog produced higher xylosidase and β-glucosidase activities and detectable endopeptidase, though these activities also fluctuated during the colonization period.
4. Unlike the other activities measured, esterase activities in the River Clywedog were correlated with cell densities (P<0.05). When extracellular esterase activities per cell were calculated, the oligotrophic biofilm was found to contain about twice as much extracellular esterase activity as the more eutrophic River Clywedog biofilm.
63 citations