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ENZYMIC DEGRADATION OF CEREAL HEMIGELLULOSES II. PATTERN OF PENTOSAN DEGRADATION
Author(s) -
Preece I. A.,
MacDougall Myra
Publication year - 1958
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1958.tb01414.x
Subject(s) - xylobiose , xylose , arabinose , chemistry , enzyme , biochemistry , xylan , hydrolysis , degradation (telecommunications) , xylanase , glycoside hydrolase , food science , fermentation , telecommunications , computer science
Using water‐soluble araboxylan of rye as substrate, it is shown that enzymic degradation involves four enzymes or enzyme systems: (a) arabinosidase, liberating free arabinose from araboxylan and from oligosaccharides; (b) endoxylanase, degrading xylan chains, whether or not these carry arabinose side chains; (c) exoxylanase, producing xylobiose from araboxylan and from oligosaccharides after some degree of arabinose removal has been achieved; and (d) xylobiase, liberating free xylose from xylobiose and, perhaps, also from xylotriose. The first detectable low‐molecular product of the joint action of these enzymes is arabinose; xylobiose and xylose appear in detectable quantities somewhat later, and higher oligosaccharides later still. Oligosaccharides with back‐bone chains of up to six xylose residues have been observed, these carrying varying proportions of arabinose residues in side chains. Different raw cereals carry all four enzyme systems, but in different proportions; the malting enhancement of pentosanase activity in barley is small compared with the enhancement of β‐glucanase activity.