Extraction and Assay of Acetic Acid Esterase From Malted Barley*

Humberstone, F.J.; Briggs, D. E.

doi:10.1002/j.2050-0416.2000.tb00037.x

Cited by 15 publications

(7 citation statements)

References 22 publications

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“…It is believed that these must be removed by esterases to facilitate the degradation of the polysaccharide by carbohydrases, as in the case in ruminant guts 3,8,[15][16][17][18]26 . We have detected acetyl esterase and feruloyl esterase activities in germinated barley and have discussed assay methods for them [15][16][17][18] . We also detected insoluble esterase activities.…”

Section: -2863(9'8-32mentioning

confidence: 99%

Partial Purification of Acetic Acid Esterase from Malted Barley

Humberstone

Briggs

2002

Journal of the Institute of Brewing

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Partial purifications (84, 114 and 390 fold) of a soluble acetic acid esterase from barley malt that degrades diacetin have been achieved. Enzyme recoveries were 20%, 20% and 25% in three consecutive runs. Initial problems of high viscosity and colour in the extract were overcome with the use of batch-elution anion exchange chromatography. This was followed by gradient elution anion exchange chromatography and gel filtration chromatography, which gave the greatest purification, but which gave erratic estimates of the molecular weight of the enzyme (40, 48 and 84 kDa). The apparent Km value of the acetyl esterase was tentatively estimated to be 25mM diacetin.

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Section: -2863(9'8-32mentioning

confidence: 99%

Partial Purification of Acetic Acid Esterase from Malted Barley

Humberstone

Briggs

2002

Journal of the Institute of Brewing

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“…Nonetheless, it is evident that significant quantities of arabinoxylan do survive the malting process and the question is begged why this is. Perhaps it reflects the substitution of the polymer with ester‐linked ferulate and acetate and it is also thought to relate to the arabinosyl side chains interfering with xylanase action . Alternatively, it may be that there are materials endogenous to the grain that inhibit xylanase.…”

Section: Introductionmentioning

confidence: 99%

An investigation of two xylan-degrading enzymes and a novel xylanase inhibitor in malted barley

et al. 2013

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Two enzymes with activity on xylan and xylan-based substrates were isolated from malted barley. One appears to be relatively anionic and the other more cationic. Both are endo-acting enzymes. The first of these was studied in more detail and shown to be of molecular weight ca. 59,000 and capable of acting through the pH range 5-7.5. It is relatively heat tolerant, with 30% of its activity surviving for 30 min at 70 C. A low-molecular-weight (ca. 1300) inhibitor of xylanase that developed during germination was investigated. Its potency was not lowered by treatment with proteolytic enzymes, but treatment with polyvinylpolypyrrolidone did reduce its impact. Ultraviolet spectrophotometry and Fourier transform infrared spectroscopy, as well as staining with Folin-Ciocalteu reagent, indicated the presence of phenolic species, while mass spectroscopy studies suggested the presence of arabinose and possibly poly-hexose. The presence of material that stained with aniline phthalate would be consistent with the presence of reducing sugar in the inhibitor.

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“…Much lower levels of acetic acid were released (as compared to ferulic acid), amounting to approximately 60 µg per 100 mg cell walls. This appears to be the first report of an association of acetyl residues with the cell walls of the starchy endosperm of barley, although an acetic acid esterase located in barley has been described which can release acetic acid from walls isolated from wheat 19 . A ferulic acid esterase has been demonstrated in barley, although its activity decreases during germination contrary to what is generally anticipated from an enzyme with an a priori role in endosperm degradation 24 .…”

Section: (Mkiwxmsr Sj [Eppw [Mxl Ir^]qiwmentioning

confidence: 76%

Enzymic Digestion of Walls Purified from the Starchy Endosperm of Barley

Kanauchi

Bamforth

2002

Journal of the Institute of Brewing

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Cell walls have been purified from the starchy endosperm of barley. Xylanases can effect the release of β-glucan from these walls, but β-glucanases do not release pentosan. Feruloyl esterase and xyloacetylesterase, with commensurate release of ferulic acid and acetic acid respectively, can effect some solubilisation of glucan. Digestion of the pentosan layer and of the feruloyl and acetyl esterification does not appear to be a prerequisite for glucan degradation. However, no more than 15% of the total β-glucan in the wall could be extracted, suggesting that some factor other than one identified in this study is limiting the solubility of this polymer.Key words: Barley, cell walls, β-glucan, pentosan, starchy endosperm. -2863(9'8-32The cell walls in the starchy endosperm of the barley kernel are claimed to comprise some 75% β-(1→3)(1→4)-glucan, 20% arabinoxylan and 5% protein, plus traces of other constituents, including ferulic acid 13 . The wall polysaccharides are detrimental to brewing performance if not efficiently degraded during malting and mashing 4,6 . However, there is positive interest in the β-glucan component as a useful source of soluble dietary fibre 20 and ferulic acid as an antioxidant supplement 23 . Furthermore, for barley to be efficiently used as a feedstock in any fermentation-based process will require the efficient digestion of the cell walls, as a source of fermentable sugar per se and also to facilitate access to the starch that such walls encase.Remarkably, it is only recently that systematic attempts have been made to understand the manner by which the components of these walls interact, viz the architecture of the walls. As the basis of our studies in this area we have previously used denatured barley flours denuded of starch as a crude cell wall 7,21,22 . We have evaluated the ability of Trichoderma viride to grow on such materials, thereby gaining some insight into the range of enzymes required by the organism in order to degrade the walls 21 . Furthermore, we have digested the preparations using a range of purified enzymes, highlighting that several activities are capable of releasing glucan and arabinoxylan from the walls 22 . In this way, we have arrived at a simple model for the wall structure, which involves a masking of β-glucan by an outer layer of arabinoxylan, to which is attached ferulic acid and possibly acetic acid 7 .We were concerned, however, that the production of the base material used for the above studies involves rigorous treatments, notably refluxing in ethanol. Whilst we are confident that the material is primarily cell wall derived, it is possible that such extreme processing could introduce artefacts, for example denaturation of polymers, leading to changes in their solubility and accessibility and to spurious coating of the walls with "foreign" materials, e.g., protein. For this reason we have now isolated walls from the starchy endosperm of barley with a gentler procedure. These isolated walls have been subjected to selective enzymic attack, in pursuit of a...

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Extraction and Assay of Acetic Acid Esterase From Malted Barley*

Cited by 15 publications

References 22 publications

Partial Purification of Acetic Acid Esterase from Malted Barley

Partial Purification of Acetic Acid Esterase from Malted Barley

An investigation of two xylan-degrading enzymes and a novel xylanase inhibitor in malted barley

Enzymic Digestion of Walls Purified from the Starchy Endosperm of Barley

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