Enzymatic Production and Complete Nuclear Magnetic Resonance Assignment of the Sugar Lactulose

• Published in: Journal of agricultural and food chemistry 2004-11, Vol.52 (23), p.6983-6990
• Main Authors: Mayer, Jürgen, Conrad, Jürgen, Klaiber, Iris, Lutz-Wahl, Sabine, Beifuss, Uwe, Fischer, Lutz
• Format: Article
• Language: English
• Subjects: Aspergillus oryzae; Aspergillus oryzae - enzymology; beta-galactosidase; beta-Galactosidase - metabolism; beta-glycosidase; Bioconversions. Hemisynthesis; Biological and medical sciences; bioreactors; Biotechnology; Cellulases - metabolism; enzymatic treatment; fructose; Fructose - metabolism; Fundamental and applied biological sciences. Psychology; Isomerism; lactose; Lactose - metabolism; lactulose; Lactulose - biosynthesis; Lactulose - chemistry; Magnetic Resonance Spectroscopy; Methods. Procedures. Technologies; nuclear magnetic resonance spectroscopy; O-glycoside hydrolases; Pyrococcus; Pyrococcus furiosus; Pyrococcus furiosus - enzymology
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf048912y

The enzymatic transgalactosylation from lactose to fructose leading to the prebiotic disaccharide lactulose was investigated using the β-galactosidase from Aspergillus oryzae and the hyperthermostable β-glycosidase from Pyrococcus furiosus (CelB). The conditions for highest lactulose yields relative to the initial lactose concentration were established on a 1 mL scale. Dependent on the initial molar ratio of lactose to fructose, more or fewer oligosaccharides other than lactulose were generated. Bioconversions on a 30 mL scale in a stirred glass reactor were performed, and lactulose yields of 46 mmol/L (44% relative to lactose) for CelB and 30 mmol/L (30% relative to lactose) for A. oryzae β-galactosidase were achieved. Only