title: Simultaneous catalysis and product separation by cross-linked enzyme crystals.
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.
authors.affiliation: Laboratory of Bioprocess Engineering, Helsinki University of Technology, P.O. Box 6100, FIN- 02015 HUT, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Leisola
authors.forename: J
authors.initials: J
authors.lastname: Jokela
authors.forename: J
authors.initials: J
authors.lastname: Finell
authors.forename: O
authors.initials: O
authors.lastname: Pastinen
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000378:metabolism*; D001089:Arabinose / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D003460:Crystallization; D004187:Disaccharides / Q000096:biosynthesis / Q000302:isolation & purification*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D009844:Oligosaccharides / Q000096:biosynthesis / Q000302:isolation & purification*; D010429:Pentoses / Q000378:metabolism; D012266:Ribose / Q000302:isolation & purification* / Q000378:metabolism; D012995:Solubility; D013302:Streptomyces / Q000201:enzymology; D014242:Trichoderma / Q000201:enzymology; D043325:Xylan Endo-1,3-beta-Xylosidase; D014994:Xylose / Q000096:biosynthesis / Q000302:isolation & purification*; D014995:Xylosidases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004187:Disaccharides; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D009844:Oligosaccharides; D010429:Pentoses; C100182:ribulose; D012266:Ribose; D014994:Xylose; D001089:Arabinose; D014995:Xylosidases; D043325:Xylan Endo-1,3-beta-Xylosidase; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase; C004173:xylobiose