Hydrophobic Complexation Promotes Enzymatic Surfactant Synthesis from Alkyl Glucoside/Cyclodextrin Mixtures

Abstract

The unique ability of cyclodextrin glycosyltransferase to form and utilize the cyclic maltooligosaccharide cyclodextrin (CD) makes this enzyme an attractive catalyst for the synthesis of alkyl glycosides. Here, we characterize the sugar headgroup elongation of alkyl glucosides (acceptor) via two transglycosylation reactions from either a linear (maltohexose) or a cyclic (CD) glycosyl donor. Inclusion complex formation overcomes both poor substrate solubility and aggregation. We have used pure alkyl glucosides and αCD as model compounds. The complex between CD and alkyl glucoside was efficiently used as a substrate. Kinetic and thermodynamic measurements allow the prediction of the optimal synthesis conditions. This optimum corresponds to the transition between a donor-limiting and an acceptor-limiting regime. The resulting rational design should lead to the practical development of a cost-efficient industrial synthesis. Our findings with respect to the importance of complexation should also readily apply to other enzymatic systems.

Enhanced 2-O-α-d-Glucopyranosyl-l-ascorbic Acid Synthesis through Iterative Saturation Mutagenesis of Acceptor Subsite Residues in Bacillus stearothermophilus NO2 Cyclodextrin Glycosyltransferase

“…CGTase catalyzes the synthesis of AA-2G via disproportionation when using linear oligosaccharides as glucosyl donors . The linear glucosyl donors are cleaved to release glucose, maltose, or maltotriose. , The acceptor substrate binds close to the +1 subsite and then moves into the +1 subsite after cleavage of the linear oligosaccharide (Figure A). The product of the initial reaction is AA-2G n ( n denotes the number of glucosyls attached to l -AA).…”

Enhanced Synthesis of 2-O-α-d-Glucopyranosyl-l-ascorbic Acid from α-Cyclodextrin by a Highly Disproportionating CGTase

“…Secondary disproportionation provides a reasonable explanation for the high preponderance of AA-2G as a transglucosylation product, as follows. CGTase is thought to cleave linear donor substrates with release of G 2 units from the reducing end. , Assuming the same cleavage pattern for l -AA glucosides whereby l -AA is recognized as the reducing-end residue, AA-2G 6 for example would be converted into AA-2G and the remaining maltopentosyl moiety might be transferred to another l -AA acceptor to give AA-2G 5 . Knowing the product distribution due to disproportionating transglucosylation from maltohexaose (Figure B), we were able to roughly estimate that the relative contributions of direct coupling to formation of l -AA glucosides from α-cyclodextrin were only approximately one-sixth that of disproportionation (Scheme ).…”

A new ratiometric electrochemical sensor for sensitive detection of bisphenol A based on poly-β-cyclodextrin/electroreduced graphene modified glassy carbon electrode

“…On the other hand, cyclodextrins (CDs), oligosaccharides composed of six, seven, or eight glucose units (α-, -, or γ-CD, respectively), are toroidal in shape with a hydrophobic inner cavity and a hydrophilic exterior [24][25][26][27][28][29]. Based on the hydrophobic interaction between guests and CD host and the shape selectivity of the CD's cavity, CDs can bind selectively various organic, inorganic, and biological guest molecules in their cavities to form stable host-guest inclusion complexes.…”