Esterase wheat

Cummins I, Burnet M, Edwards R (2001) Biochemical characterisation of esterases active in hydrolysing xenobiotics in wheat and competing weeds. Physiol Plant 113 477 185... 

Feruloyl esterase activity was first detected in culture filtrates of Strepto-myces olivochromogenes (49), and has thereafter also been reported for some hemicellulolytic fungi (Table III). A partially purified feruloyl esterase from S. commune liberated hardly any ferulic acid without the presence of xylanase (65). Very recently a feruloyl esterase was purified from Aspergillus oryzae (Tenkanen, M. Schuseil, J. Puls, J. Poutanen, K., /. Biotechnol, in press). The enzyme is an acidic monomeric protein having an isoelectric point of 3.6 and a molecular weight of 30 kDa. It has wide substrate specificity, liberating ferulic, p-coumaric, and acetic acids from steam-extracted wheat straw arabinoxylan. 

Table 2.2.3.3 Determination of the carboxypeptidase and esterase side-activities of Si HNL in comparison with carboxypeptidase II from wheat. ...

Smith, M. M., and O Brian, T. P., 1979, Distribution of auto fluorescence and esterase and peroxidase activities in the epidermis of wheat roots, Austr. J. Plant Physiol. 6 201-219. 

Esterases. Acetyl esterase (EC 3.1.1.6) removes acetyl esters from acetylated xylose and short-chain xylo-oligomers. It s polymeracting counterpart, acetyl xylan esterase (EC 3.1.1.72), has a similar activity, but prefers polymeric xylan.244 In addition to acetate-specific enzyme detection kits, HPLC or GC analysis of acetate release from native extracted xylan and chemically acetylated xylan, colorimetric substrates, such as p-nitrophenol acetate and /3-napthyl acetate, or the fluorometric substrate, 4-methylumbelliferyl acetate are also used to assay acetyl esterases.244,253 The third esterase, ferulic acid esterase (EC 3.1.1.73), hydrolyzes the ester bond between ferulic acid or coumaric acid and the arabinose side chain of arabinoxylan. Assays for this activity are usually carried out using starch-free wheat bran or cellulase-treated gramineous biomass as a substrate and monitoring ferulic or coumaric acid released by HPLC or TLC. When preparing enzyme-treated substrates, care must be taken to employ phenolic-acid-esterase-free cellulases.244 Other substrates include methyl and ethyl esters of the phenolic acids, as well as finely ground plant biomass.240,254,255... 

Yet another example of the catalytic triad has been found in carboxypeptidase II from wheat. The structure of this enzyme is not significantly similar to either chymotrypsin or subtilisin (Figure 9.15). This protein is a member of an intriguing family of homologous proteins that includes esterases such as acetylcholine esterase and certain lipases. These enzymes all make use of histidine-activated nucleophiles, but the nucleophiles may be cysteine rather than serine. 

ANL Aspergillus niger lipase CAL Candida antarctica lipase CCL lipase from Candida Rhizopusjaponicus lipase RTE Rhodosporium toruloides esterase WGL wheat germ... 

Consistent with the hybridisation protocol, Northern blots confirmed that the N. crassa gene was expressed on sugar beet pulp and absent on sucrose and wheat bran. This expression profile is similar to the characteristics of other type B ferulic acid esterases.5 6... 

In contrast to the stability of endogenous ABA-GE, applied ABA-GE is rapidly hydrolyzed. For example, in Ricinus leaves, applied ABA-GE was hydrolyzed prior to uptake and translocation of free ABA in the phloem [119]. In wheat seedlings, ABA-GE was split by glucosidases rather than esterases [127], When radioactive ABA-GE was applied to cell suspension cultures of Lycopersicon, free ABA appeared in the medium and cells within 20 minutes, but the radioactive conjugate was not detected in the cells until much later [125]. Hydrolysis presumably took place at the plasma membrane, the free acid then entered the cell and was conjugated again inside the cell. These observations indicate that ABA-GE as such cannot enter cells. 

Belzunces, L.P., Lenfant, C., Di Pasquale, S. and Colin, M.E. (1994). In vivo and in vitro effects of wheat germ agglutinin and Bowman-Birk soybean trypsin inhibitor, two potential transgene products, on midgut esterase and protease activities from Apis mellifera. Comp. Biochem. Physiol. 109B, 63-69. 

Ferulic acid is the major cinnamic acid found in a variety of plant cell walls. Com fiber contains about 3% femlic acid. Wheat bran is another source of ferulic acid (0.5-1%). Faulds et al. 226) developed a laboratory scale procedure to produce free femlic acid (5.7 g) from wheat bran (1 kg) by using a Trichoderma xylanase preparation and A, niger femlic acid esterase. Using filamentous fungi, a two-stage process for vanillin formation was developed in which a strain of A. niger was first used to convert femlic acid to vanillic acid, which was then reduced to vanillin by a laccase-deficient strain of Pycnoporus cinnabarinus 227). 

The presence of feruloyl esterase activity was first detected in culture filtrates of Streptomyces olivochromogenes grown on oats spelt xylan and wheat bran (iJ) and have subsequently been found in a number of bacterial and fungal... 

PLLA, PDLA, PLDLA Rod diam. 2 mm, 1 10mm Mn 2.2 PBS (pH 7.2) containing either porcine liver esterase (PLE), wheat germ lipase (WGL), porcine pancreatic lipase (PPL), or Rhizopus delemar Wpase (RDL) 37 Wt. loss Degradation rate RDL>PPL>PLE>WGL>PBS Copolymers degrade faster than homopolymers 23... 

Zhang J, Siika-aho M, Tenkanen M, Viikari L. (2011). The role of acetyl xylan esterase in the solubilization of xylan and enzymatic hydrolysis of wheat straw and giant reed. Biotechnol Biofuels, 4(1), 60. 

Studies on the early responses of aleurone layers to GA have shown that a-amy-lase is not the first enzyme to be secreted. Within 5 h of the addition of GA to isolated aleurone layers of barley (cv. Betzes) there is increased secretion into the surrounding medium of several hydrolytic enzymes, including an ATP-ase, phytase, j -glucosidase and phosphomonoesterase, as well as some soluble carbohydrate [96] (probably sucrose). Similar observations were made using GA-treated half-grains of both barley and wheat (the distal embryoless half), although in barley additional enzymes, e.g. an esterase, phosphodiesterase and a-galactosidase were also found to be secreted early [96]. From the limited information available to date it appears that some enzymes which are secreted early after GA addition (e.g. phosphomonoesterase and phosphodiesterase) do so in response to lower concentrations of GA than do the later ones (e.g. a-amylase) [97]. Furthermore, a-amylase and proteinase, which are secreted simultaneously, have identical GA dose-response curves (Fig. 7.5A and B). There are exceptions, however, and further work on more enzymes is required to determine if the sequence of enzyme production by aleurone tissue is related to GA concentration in the cells. 

In addition to the esterase, a wheat lipase occurs errriched in the bran. A rise in free fatty acids observable during flour storage also involves lipases from metabolism of microorganisms present in flour. 

Solubilisation of the lipases from both oat and wheat flours also leads to the release of esterase activity. Some partial separation of activity could be achieved in the case of wheat flour by differential solubilisation with varying concentrations of Tween 20. This technique also leads to some enrichment of lipase activity with respect to protein. 

The solubilised oat and wheat lipases have been fractionated by ion-exchange chromatography in the presence of detergent. Two distinct lipase peaks were separated in the case of wheat extracts, both of which also contained esterase activity. Further work to characterise and purify these peaks is being undertaken. 

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