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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 synthesis of relevant GE model substrates presented here may provide a valuable tool for the screening, selection and development of industrially relevant GEs for delignification of biomass.
Abstract: Lignin-carbohydrate complexes (LCCs) are believed to influence the recalcitrance of lignocellulosic plant material preventing optimal utilization of biomass in e.g. forestry, feed and biofuel applications. The recently emerged carbohydrate esterase (CE) 15 family of glucuronoyl esterases (GEs) has been proposed to degrade ester LCC bonds between glucuronic acids in xylans and lignin alcohols thereby potentially improving delignification of lignocellulosic biomass when applied in conjunction with other cellulases, hemicellulases and oxidoreductases. Herein, we report the synthesis of four new GE model substrates comprising α- and ɣ-arylalkyl esters representative of the lignin part of naturally occurring ester LCCs as well as the cloning and purification of a novel GE from Cerrena unicolor (CuGE). Together with a known GE from Schizophyllum commune (ScGE), CuGE was biochemically characterized by means of Michaelis–Menten kinetics with respect to substrate specificity using the synthesized compounds. For both enzymes, a strong preference for 4-O-methyl glucuronoyl esters rather than unsubstituted glucuronoyl esters was observed. Moreover, we found that α-arylalkyl esters of methyl α-D-glucuronic acid are more easily cleaved by GEs than their corresponding ɣ-arylalkyl esters. Furthermore, our results suggest a preference of CuGE for glucuronoyl esters of bulky alcohols supporting the suggested biological action of GEs on LCCs. The synthesis of relevant GE model substrates presented here may provide a valuable tool for the screening, selection and development of industrially relevant GEs for delignification of biomass. Biotechnol. Bioeng. 2015;112: 914–922. © 2014 Wiley Periodicals, Inc.
53 citations
TL;DR: There appears to be a positive correlation between the ability of the yeast to form esterase and the level of esters present in fermentations accomplished by that yeast.
Abstract: An esterase (carboxylic acid hydrolase EC 3 1.1.1.) has been prepared from Saccharomyces cerevisiae. This esterase is active at pH 4.4 and, though it is unstable in solution, it can be maintained in an active form either by lyophilization or by coupling to an affinity gel. At pH 4.4, yeast esterase can hydrolyse between 20 and 40% of the esters commonly present in beer, and it is capable of synthesizing ethyl acetate from ethanol and acetic acid in a simple buffered solution without the provision of a co-factor. Different yeast strains yield different amounts of esterase, and there appears to be a positive correlation between the ability of the yeast to form esterase and the level of esters present in fermentations accomplished by that yeast.
53 citations
TL;DR: An extracellular alkaline proteinase produced by Candida lipolytica was purified through iso-propanol and ammonium sulfate precipitation, decolorization with DEAE-cellulose, gel filtration with Sephadex G–100 and ion-exchange chromatography onDEAE-SephadeX A–50 indicated that this enzyme was distinguishable from other microbial alkalineproteinases so far studied.
Abstract: An extracellular alkaline proteinase produced by Candida lipolytica was purified through iso-propanol and ammonium sulfate precipitation, decolorization with DEAE-cellulose, gel filtration with Sephadex G–100 and ion-exchange chromatography on DEAE-Sephadex A–50. The optimum pH of its caseinolytic activity was 9.0, and this activity was completely inactivated with DFP but not with chelating reagents, PCMB, STI, TLCK, TPCK, or SSI. This enzyme also hydrolyzed salmin and synthetic esters, such as Bz. Arg. OEt, Bz. His. OMe, Tos. Lys. OMe or Ac. Tyr. OEt, and the optimum pH of its esterase activity was 8.0. The molecular weight of the enzyme was estimated to be about 30,000 by the gel filtration method. These facts indicated that this enzyme was distinguishable from other microbial alkaline proteinases so far studied.
53 citations
TL;DR: Comparison of 10 α-naphthyl acetate esterase isozymes resolved by electrophoresis revealed seven interstrain differences and malathion resistance in this insect is due to an altered ester enzyme, just as is true for several dipterans.
Abstract: Malathion resistance in a strain of Plodia interpunctella (Hubner) was highly specific for malathion and was suppressed by nontoxic carboxylesterase inhibitors. Fifth instars of the resistant strain had 33 times as much malathion carboxylesterase activity but only 0.30 times as much α-naphthyl acetate esterase activity as larvae of a susceptible strain. Resistance was controlled by a single autosomal gene or closely linked set of genes. Resistance and malathion carboxylesterase were inherited as dominant and codominant factors, respectively, and were genetically linked. Thus, malathion resistance in this insect is due to an altered esterase, just as is true for several dipterans. Comparison of 10 α-naphthyl acetate esterase isozymes resolved by electrophoresis revealed seven interstrain differences.
53 citations
TL;DR: The simultaneous enzymic liberation of acetyl groups from xylan and glucomannan clearly enhanced the action of xylan‐ and mannan‐degrading enzymes, thus increasing the hydrolysis yield significantly, however, none of the esterases was able to remove all acetyl substituents when acting alone and simultaneous action of two esterase was needed for complete deacetylation.
Abstract: Xylans and mannans contain different esterified substituents such as acetyl, feruloyl and p-coumaroyl side groups. The functions of hemicellulose-deacetylating esterases of Trichoderma reesei and Aspergillus oryzae are discussed in this paper. Both fungi produce multiple esterases and two different esterases were isolated from both T. reesei and A. oryzae. The enzymes differed significantly in their substrate specificities. Acetyl xylan esterase of T. reesei was highly active on polymeric xylan but was unable to remove acetyl substituents from glucomannan or phenolic substituents from wheat straw arabinoxylan. Another esterase, acetyl esterase from T. reesei, had activity only towards short oligomeric and monomeric acetates derived both from xylan and glucomannan. The acetyl glucomannan esterase of A. oryzae was most active towards polymeric glucomannan, but was also able to remove acetyl groups from xylan. The only esterase studied which was active against phenolic substituents in arabinoxylans was the feruloyl esterase from A. oryzae. Feruloyl esterase had the widest substrate specificity of the esterases studied. It was also able to act on acetyl groups both in xylan and in glucomannan. The simultaneous enzymic liberation of acetyl groups from xylan and glucomannan clearly enhanced the action of xylan- and mannan-degrading enzymes, thus increasing the hydrolysis yield significantly. However, none of the esterases was able to remove all acetyl substituents when acting alone and simultaneous action of two esterases was needed for complete deacetylation.
53 citations