Synthesis and Hydrolysis of 1,3‐β‐Xylosidic Linkages by Endo‐1,4‐β‐xylanase of Cryptococcus albidus

Abstract

Purified extracellular endo‐1,4‐β‐xylanase (EC 3.2.1.8) of the yeast Cryptococcus albidus was found to catalyze not only the known 1,4‐β‐transfer, but an alternative transglycosylation reaction leading to the formation of 1,3‐β‐glycosidic linkages. From a mixture of products of β‐xylanase degradation of phenyl β‐D‐xylopyranoside three xylooligosaccharide fractions, differring chromatographically from the 1,4‐β‐linked products, were isolated by preparative paper chromatography. Their structure was elucidated by mass spectrometry, 13C‐NMR spectroscopy and enzymic hydrolysis by β‐xylanase and β‐xylosidase. The isomeric xylotriose was identified as 3‐O‐β‐D‐xylopyranosyl‐4‐O‐β‐D‐xylopyranosyl‐D‐xylose. The fraction of isomeric tetrasaccharides was found to be represented mainly by 4‐O‐β‐D‐xylopyranosyl‐3‐O‐β‐D‐xylopyranosyl‐4‐O‐β‐D‐xylopyranosyl‐D‐xylose. The xylooligosaccharides containing one 1,3‐β‐linkage were also produced on the enzyme treatment of 1,4‐β‐xylotriose and 1,4‐β‐xylan. When treated with the enzyme responsible for their synthesis, the isomeric xylooligosaccharides were hydrolyzed at the 1,3‐β‐linkage, despite the fact the enzyme does not attack 1,3‐β‐xylan. The results are interpreted in the relation to the characterized four‐subsite substrate‐binding site of the enzyme.

Use of Residual Biomass from the Textile Industry as Carbon Source for Production of a Low-Molecular-Weight Xylanase from Aspergillus oryzae

“…Indeed, the effect of transglycosylation could explain the constant rate of hydrolysis obtained by the DNS method after 12 h of incubation ( Table 5). As reported by Biely and Vranská [47], the transfer of glycosyl groups is a well-known activity of glycosidases and glycanases. Consistent with the findings of these authors, the enzyme acts on oligosaccharides or aryl glycosides (e.g., invertase, β-galactosidase, A. niger β-glucosidase) to catalyze the formation of various positional isomers of the oligosaccharides.…”

Xylanases of Microorganisms

“…Ââàжàþòü [11], ùî òðàíñгë³êîçèëþâàííÿ åíäîíóêëåàçàìè ïðèâîäèòü äî óòâîðåííÿ ïðîäóêò³â, ÿê³ ì³ñòÿòü ò³ ж ñàì³ çâ'ÿçêè, ùî ³ ñóáñòðàò, îñê³ëüêè âîíè ì³ñòÿòü ñòåðåîñïåöèф³÷í³ ì³ñöÿ çâ'ÿçóâàííÿ íà áóäü ÿê³é ñòîðîí³ êàòàë³òè÷íîгî ñàéòó. ßê ïîâ³äîìëÿëîñü [9], êñèëàíàçà Cryptococcus albidus óòâîðþº 1,3 β d çâ'ÿçêè çàâäÿêè ðåàêö³¿ òðàíñгë³êîçèëþâàííÿ. …”