Utilisation of Cyclodextrin Glycosyltransferases (Cgtases) in Synthesis of Alkyl Glycosides

Session: 
PS2 Poster session 2 Even numbers
Code: 
P6
Location (hall): 
Foyer
Start/end time: 
Tuesday, July 2, 2019 - 15:45 to 17:15
Kazi Zubaida Gulshan
Ara

Kazi Zubaida Gulshan Ara1, Eva Nordberg Karlsson1, Patrick Adlercreutz1, Pontus Lundemo, Mohd Younis  Rather2

1Dept. of Chemistry, Division of Biotechnology Lund University, Lund, Sweden, 2Dept. of Pharmacology, Government medical College Srinagar, Kashmir, India

Non-ionic surfactants such as alkyl glycosides have a wide range of applications which made them an interesting target for biotechnological industries. It has been shown that elongation of the hydrophilic group makes them milder to cells and tissues, which make elongation of the carbohydrate part of alkylglycosides of particular interest. The elongation process of an alkyl glycoside can be achieved very efficiently by using α-cyclodextrin as donor in coupling reactions catalyzed by CGTase [1]. Cyclodextrin glucanotransferases (CGTases) (EC 2.4.1.19) belongs to GH family 13 and are also capable of catalysing cyclization, hydrolysis and disproportionation by using substrates like starch. This opens up the possibility to synthesize a whole range of highly interesting surfactants with elongated carbohydrate groups. 

Recently we have characterized a novel CGTase (CspCGT13) from Carboxydocella, which was used to elongate dodecyl-β-maltoside (β-DDM) [2]. The enzyme displayed high coupling activity using γ-CD as donor and β-DDM as acceptor. CspCGT13 was also efficient in elongating β-DDM by using α-CD [3]. However, in both cases the disproportionation reaction was dominating over the coupling reaction which limits the usability of this enzyme for producing well-defined alkyl glycosides (table 1 & 2). On the other hand the high disproportionation reactivity of CspCGT13 makes it an interesting candidate for synthesizing alkyl polyglycosides (APGs). We have also used site-directed mutagenesis approach to improve the coupling activity and the primary results shows improved coupling/disproportionation ratio.

Table 1: Coupling and disproportionation activities of CGTase from Carboxydocella. Dodecyl-β-maltoside was used as acceptor for coupling and disproportionation. 
And Table 2: Product profiles of different CGTases in coupling reaction using Dodecyl-β-maltoside as accceptor and α-CD as donor. The primary coupling product is Dodecyl-β-maltooctaoside (β-DDMO).

Acknowlegements

This project was supported by FORMAS (Grant 2015-769).

References: 
  1. Svensson, D.; Ulvenlund, S.; Adlercreutz, P. Enzymatic route to alkyl glycosides having oligomeric head groups. Green Chem. 2009b. 11:1222-1226. 
  2. Ara, K Z G.; Lundemo, P.; Fridjonsson, O. H.; Hreggvidson, G. O.; Adlercreutz, P.; Karlsson, E N. A CGTase with high coupling activity using γ-cyclodextrin isolated from a novel strain clustering under the genus Carboxydocella. Glycobiology. 2015. 25, 5, p. 514-523.
  3. Rather, Y.; Ara, KZG.; Karlsson, E N.; Adlercreutz, P. Characterization of cyclodextrin glycosyltransferases (CGTases) and their application for synthesis of alkyl glycosides with oligomeric head group. Process Biochem. 2015. 50, 5, p. 722-728.
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