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Hidden Reaction: Mesophilic Cellobiose 2-Epimerases Produce Lactulose.
- Source :
-
Journal of agricultural and food chemistry [J Agric Food Chem] 2017 Mar 29; Vol. 65 (12), pp. 2530-2539. Date of Electronic Publication: 2017 Mar 15. - Publication Year :
- 2017
-
Abstract
- Lactulose (4-O-β-d-galactopyranosyl-d-fructofuranose) is a prebiotic sugar derived from the milk sugar lactose (4-O-β-d-galactopyranosyl-d-glucopyranose). In our study we observed for the first time that known cellobiose 2-epimerases (CEs; EC 5.1.3.11) from mesophilic microorganisms were generally able to catalyze the isomerization reaction of lactose into lactulose. Commonly, CEs catalyze the C2-epimerization of d-glucose and d-mannose moieties at the reducing end of β-1,4-glycosidic-linked oligosaccharides. Thus, epilactose (4-O-β-d-galactopyranosyl-d-mannopyranose) is formed with lactose as substrate. So far, only four CEs, exclusively from thermophilic microorganisms, have been reported to additionally catalyze the isomerization reaction of lactose into lactulose. The specific isomerization activity of the seven CEs in this study ranged between 8.7 ± 0.1 and 1300 ± 37 pkat/mg. The results indicate that very likely all CEs are able to catalyze both the epimerization as well as the isomerization reaction, whereby the latter is performed at a comparatively much lower reaction rate.
- Subjects :
- Bacterial Proteins genetics
Bacterial Proteins metabolism
Bacteroides enzymology
Bacteroides genetics
Biocatalysis
Carbohydrate Epimerases genetics
Carbohydrate Epimerases metabolism
Cellobiose chemistry
Enzyme Stability
Flavobacterium enzymology
Flavobacterium genetics
Lactose metabolism
Lactulose chemistry
Bacterial Proteins chemistry
Carbohydrate Epimerases chemistry
Cellobiose metabolism
Lactulose metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1520-5118
- Volume :
- 65
- Issue :
- 12
- Database :
- MEDLINE
- Journal :
- Journal of agricultural and food chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 28252294
- Full Text :
- https://doi.org/10.1021/acs.jafc.6b05599