645-03-4Relevant articles and documents
Production of keto-disaccharides from aldo-disaccharides in subcritical aqueous ethanol
Gao, Da-Ming,Kobayashi, Takashi,Adachi, Shuji
, p. 998 - 1005 (2016/05/09)
Isomerization of disaccharides (maltose, isomaltose, cellobiose, lactose, melibiose, palatinose, sucrose, and trehalose) was investigated in subcritical aqueous ethanol. A marked increase in the isomerization of aldo-disaccharides to keto-disaccharides was noted and their hydrolytic reactions were suppressed with increasing ethanol concentration. Under any study condition, the maximum yield of keto-disaccharides produced from aldo-disaccharides linked by β-glycosidic bond was higher than that produced from aldo-disaccharides linked by α-glycosidic bond. Palatinose, a keto-disaccharide, mainly underwent decomposition rather than isomerization in subcritical water and subcritical aqueous ethanol. No isomerization was noted for the non-reducing disaccharides trehalose and sucrose. The rate constant of maltose to maltulose isomerization almost doubled by changing solvent from sub-critical water to 80 wt% aqueous ethanol at 220°C. Increased maltose monohydrate concentration in feed decreased the conversion of maltose and the maximum yield of maltulose, but increased the productivity of maltulose. The maximum productivity of maltulose was ca. 41 g/(h kg-solution).
Production of galacto-oligosaccharides by the β-galactosidase from kluyveromyces lactis: Comparative analysis of permeabilized cells versus soluble enzyme
Rodriguez-Colinas, Barbara,De Abreu, Miguel A.,Fernandez-Arrojo, Lucia,De Beer, Roseri,Poveda, Ana,Jimenez-Barbero, Jesus,Haltrich, Dietmar,Ballesteros Olmo, Antonio O.,Fernandez-Lobato, Maria,Plou, Francisco J.
experimental part, p. 10477 - 10484 (2012/07/17)
The transgalactosylation activity of Kluyveromyces lactis cells was studied in detail. Cells were permeabilized with ethanol and further lyophilized to facilitate the transit of substrates and products. The resulting biocatalyst was assayed for the synthesis of galacto-oligosaccharides (GOS) and compared with two soluble β-galactosidases from K. lactis (Lactozym 3000 L HP G and Maxilact LGX 5000). Using 400 g/L lactose, the maximum GOS yield, measured by HPAEC-PAD analysis, was 177 g/L (44% w/w of total carbohydrates). The major products synthesized were the disaccharides 6-galactobiose [Gal-β(1?6)-Gal] and allolactose [Gal-β(1?6)-Glc], as well as the trisaccharide 6-galactosyl-lactose [Gal-β(1?6)-Gal-β(1?4)-Glc], which was characterized by MS and 2D NMR. Structural characterization of another synthesized disaccharide, Gal-β(1?3)-Glc, was carried out. GOS yield obtained with soluble β-galactosidases was slightly lower (160 g/L for Lactozym 3000 L HP G and 154 g/L for Maxilact LGX 5000); however, the typical profile ith a maximum GOS concentration followed by partial hydrolysis of the newly formed oligosaccharides was not observed with the soluble enzymes. Results were correlated with the higher stability of β-galactosidase when permeabilized whole cells were used.
Engineering of glucoside acceptors for the regioselective synthesis of β-(1→3)-disaccharides with glycosynthases
Marton, Zsuzanna,Tran, Vinh,Tellier, Charles,Dion, Michel,Drone, Jullien,Rabiller, Claude
experimental part, p. 2939 - 2946 (2009/04/06)
Glycosynthase mutants obtained from Thermotoga maritima were able to catalyze the regioselective synthesis of aryl β-d-Galp-(1→3)-β-d-Glcp and aryl β-d-Glcp-(1→3)-β-d-Glcp in high yields (up to 90 %) using aryl β-d-glucosides as acceptors. The need for an aglyconic aryl group was rationalized by molecular modeling calculations, which have emphasized a high stabilizing interaction of this group by stacking with W312 of the enzyme. Unfortunately, the deprotection of the aromatic group of the disaccharides was not possible without partial hydrolysis of the glycosidic bond. The replacement of aryl groups by benzyl ones could offer the opportunity to deprotect the anomeric position under very mild conditions. Assuming that benzyl acceptors could preserve the stabilizing stacking, benzyl β-d-glucoside firstly assayed as acceptor resulted in both poor yields and poor regioselectivity. Thus, we decided to undertake molecular modeling calculations in order to design which suitable substituted benzyl acceptors could be used. This study resulted in the choice of 2-biphenylmethyl β-d-glucopyranoside. This choice was validated experimentally, since the corresponding β-(1→3) disaccharide was obtained in good yields and with a high regioselectivity. At the same time, we have shown that phenyl 1-thio-β-d-glucopyranoside was also an excellent substrate leading to similar results as those obtained with the O-phenyl analogue. The NBS deprotection of the S-phenyl group afforded the corresponding disaccharide quantitatively.
