endo-Xylanase Assay Kit (XylX6 Method)

The XylX6 assay reagent for the measurement of endo-xylanase (endo-1,4-β-xylanase) contains two components; 1) 4,6-O-(3-Ketobutylidene)-4-nitrophenyl-β-D-45-glucosyl-xylopentaoside and 2) β-xylosidase. The ketone blocking group prevents any hydrolytic action by the β-xylosidase or other exo-acting glycosidases on the XylX6 substrate. Incubation with an endo-xylanase generates a non-blocked colourimetric oligosaccharide that is rapidly hydrolysed by the ancillary β-xylosidase. The rate of formation of 4-nitrophenol is therefore directly related to the hydrolysis of XylX6 by the endo-xylanase. The reaction is terminated and the phenolate colour is developed on addition of Tris buffer solution (pH = 10.0).

Note that standard curves relating the absorbance obtained using the XylX6 assay to endo-xylanase activity on the native substrates, wheat arabinoxylan and beechwood xylan, are provided in the Supporting Information file under the Documentation tab.

endo-Xylanase Assay Kit (XylX6 Method)
Product Code
100 assays (manual) / 200 assays (auto-analyser)
200 assays (manual) / 400 assays (auto-analyser)

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Colourimetric method for the determination of endo-1,4-β-xylanase in any
sample type including crude enzyme extracts, fermentation broths or
commercial enzyme preparations

(1) 3-Ketobutylidene-GX5-β-PNP + H2O → Blocked-GXY + X(5-Y)-β-PNP

(2) X(5-Y)-β-PNP + H2O → D-xylose + PNP

       (alkaline solution)
(3) PNP → phenolate ion (yellow colour)
Note: PNP = 4-nitrophenol

Kit size:
K-XylX6-1V 100 assays (manual) / 200 (auto-analyser)
K-XylX6-2V 200 assays (manual) / 400 (auto-analyser)

Method:                         Spectrophotometric at 400/405 nm
Total assay time:           10 min
Detection limit:                5.3 x 10-4 U/mL
Application examples:
Fermentation broths, industrial enzyme preparations, animal feed, biofuels research, barley
malt analysis
Method recognition:     Novel method


  • Very cost effective
  • All reagents stable for > 4 years
  • Completely specific for endo-1,4-β-xylanase
  • Generally applicable and highly sensitive
  • Simple format. Well suited to automation
  • Excellent reproducibility
  • Standard included

Prediction of potential malt extract and beer filterability using conventional and novel malt assays.

Cornaggia, C., Evans, D. E., Draga, A., Mangan, D. & McCleary, B. V. (2019). Journal of Institute of Brewing, In Press.

Development of an automatable method for the measurement of endo-1,4-β-xylanase activity in barley malt and initial investigation into the relationship between endo-1,4-β-xylanase activity and wort viscosity.

Mangan, D., Cornaggia, C., Liadova, A., Draga, A., Ivory, R., Evans, D. E. & McCleary, B. V. (2018). Journal of Cereal Science, 84, 90-94.

Novel substrates for the automated and manual assay of endo-1,4-β-xylanase.

Mangan, D., Cornaggia, C., Liadova, A., McCormack, N., Ivory, R., McKie, V. A., Ormerod, A. & McCleary, D. V. (2017). Carbohydrate Research, 445, 14-22.

A Comparison of Polysaccharide Substrates and Reducing Sugar Methods for the Measurement of endo-1,4-β-Xylanase

McCleary, B. V. & McGeough, P. (2015). Appl. Biochem. Biotechnol., 177(5), 1152-1163.

Below you will find a link to our dedicated frequently asked questions section. Within this section you will find common questions and answers on a range of topics about the product.