Abstract
Crystalline cross-linked xylose isomerase (CLXI, EC 5.3.1.5) and xylanase (CLX, EC 3.2.1.8) were studied in a packed-bed reactor for simultaneous catalytic reaction and separation of substrates from reaction products. Streptomyces rubiginosus xylose isomerase catalyzed a slow isomerization of L-arabinose to L-ribulose and an epimerization to L-ribose. In equilibrium the reaction mixture contained 52.5% arabinose, 22.5% ribulose, and 25% ribose. In a packed-bed column filled with CLXI, a simultaneous reaction and separation resulted in fractions where arabinose concentration varied between 100-0%, ribulose between 0-55%, and ribose between 0-100%. Trichoderma reesei xylanase II hydrolyzed and transferred xylotetraose mainly to xylotriose and xylobiose. In a packed-bed column filled with CLX, xylotetraose rapidly reacted to xylobiose and xylose by a mechanism that is not yet fully understood.
Copyright 2001 John Wiley & Sons, Inc.
MeSH terms
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Aldose-Ketose Isomerases / chemistry
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Aldose-Ketose Isomerases / metabolism*
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Arabinose / metabolism
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Bacterial Proteins / chemistry
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Bacterial Proteins / metabolism*
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Catalysis
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Crystallization
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Disaccharides / biosynthesis
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Disaccharides / isolation & purification*
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Enzymes, Immobilized / chemistry
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Enzymes, Immobilized / metabolism*
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Fungal Proteins / chemistry
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Fungal Proteins / metabolism*
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Oligosaccharides / biosynthesis
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Oligosaccharides / isolation & purification*
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Pentoses / metabolism
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Ribose / isolation & purification*
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Ribose / metabolism
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Solubility
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Streptomyces / enzymology
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Trichoderma / enzymology
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Xylan Endo-1,3-beta-Xylosidase
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Xylose / biosynthesis
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Xylose / isolation & purification*
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Xylosidases / chemistry
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Xylosidases / metabolism*
Substances
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Bacterial Proteins
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Disaccharides
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Enzymes, Immobilized
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Fungal Proteins
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Oligosaccharides
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Pentoses
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ribulose
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Ribose
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Xylose
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Arabinose
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Xylosidases
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Xylan Endo-1,3-beta-Xylosidase
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Aldose-Ketose Isomerases
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xylose isomerase
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xylobiose