Reaction investigation of lactulose-producing cellobiose 2-epimerases under operational relevant conditions
| Autor: | Wolfgang Claaßen, Bo Jiang, Timo Stressler, Lutz Fischer, Wanmeng Mu, Beatrice Kuschel |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
biology Process Chemistry and Technology Thermophile Bioengineering Epilactose Cellobiose biology.organism_classification Biochemistry Catalysis 03 medical and health sciences chemistry.chemical_compound Lactulose 030104 developmental biology chemistry medicine Organic chemistry Lactose Sugar Caldicellulosiruptor saccharolyticus Isomerization medicine.drug |
| Zdroj: | Journal of Molecular Catalysis B: Enzymatic. 133:S80-S87 |
| ISSN: | 1381-1177 |
| DOI: | 10.1016/j.molcatb.2016.11.022 |
| Popis: | The cellobiose 2-epimerases (CEs) from Caldicellulosiruptor saccharolyticus ( Cs CE) and Dictyoglomus turgidum ( Dt CE) are the two CEs best investigated which are able to catalyse an epimerisation and an isomerisation reaction on lactose. However, both enzymes are thermophilic and have, so far, only been characterised under their respective optimal conditions. The CE from Caldicellulosiruptor saccharolyticus has recently been applied for epilactose and lactulose production in milk at lower temperatures. The kinetic parameters under supposedly industrial relevant conditions and the direct comparability of Cs CE and Dt CE still remain unknown and were, therefore, the object of this study. In general, Cs CE and Dt CE displayed similar reaction progresses and similar kinetic parameters. Surprisingly, the Cs CE was observed to catalyse the isomerisation reaction of lactulose into lactose and epilactose twice as efficiently ( k cat / K m ) as Dt CE. For the first time, the reaction progress for lactose, epilactose and lactulose as substrates was observed for both Cs CE and Dt CE over 48 h at 50 °C, pH 7.5. These conversions led to the same final sugar concentrations of about 30.5% ts lactose, 14.5% ts epilactose and 55% ts lactulose with both CEs. During the course of the conversions, the interrelated ratios of lactose and epilactose remained steady at about 70:30, respectively. In conclusion, both CEs were of comparable aptitude for industrial application under the conditions tested and most probably catalyse the same course of reaction. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect