Some Characteristics of β- D-Xylopyranosidases, α- L-Arabinofuranosidases and an Arabinoxylan α- L-arabinofuranohydrolase from Wheat Bran and Germinated Wheat

• Published in: Journal of cereal science Vol. 23; no. 2; pp. 169 - 180
• Main Authors: Beldman, G., Osuga, D., Whitaker, J.R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 1996; Elsevier
• Subjects: Agronomy. Soil science and plant productions; arabinoxylan; Biological and medical sciences; Cereal and baking product industries; Economic plant physiology; enzyme; Enzymes; Food industries; Fundamental and applied biological sciences. Psychology; hydrolysis; Nutrition. Photosynthesis. Respiration. Metabolism; wheat; enzyme; wheat; arabinoxylan; hydrolysis; Cereal bran; Monocotyledones; Enzyme; Germination; α-L-Arabinofuranosidase; Cereal crop; Hydrolysis; Enzymatic activity; Gramineae; Glycosidases; Angiospermae; Cereal; Hydrolases; Spermatophyta; O-Glycosidases; Wheat; Triticum aestivum
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1006/jcrs.1996.0017

Enzymes from wheat bran and germinated wheat involved in the degradation of arabinoxylan and arabinoxylooligosaccharides were investigated. Four p-nitrophenyl-α- l-arabinofuranoside hydrolysing activities (Ara fI-IV) and three p-nitrophenyl-β- d-xylopyranoside hydrolysing activities (Xyl pI-III) were identified in wheat kernels and germinating wheat. Two of these activities, Ara fI and Xyl pII, were purified about 10 000-fold from wheat bran. Both enzymes were inactive towards polymeric arabinoxylan. Ara fI produced no arabinose but some xylose from arabinoxylooligosaccharides, while Xyl pII gave only xylose upon incubation with this substrate. An arabinoxylan arabinofuranohydrolase (AXH) was found in wheat bran and germinated wheat. This enzyme was active towards the polymeric substrate, but was unable to hydrolyse p-nitrophenyl-α- l-arabinofuranoside. The M rs of these enzymes were determined by size exclusion chromatography and were in the range of 40–50 000, except for Ara fIII, for which a M rof 104 000 was determined. During germination, the levels of these enzymes increased markedly between the third and fifth day, after which some of them decreased again by the seventh day. Ara fI-IV were inhibited strongly by arabinonic acid-γ-lactone, while xylonic acid-γ-lactone was a good inhibitor of Xyl pI-III. The latter lactone also inhibited Ara fI. Neither of these lactones inhibited AXH. Endoxylanase activity was demonstrated but not quantified.