|Kremnicky, Lubomir - SLOVAK ACADEMY|
|Mastihuba, Vladimir - SLOVAK ACADEMY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 3, 2003
Publication Date: July 3, 2003
Citation: Kremnicky, L., Mastihuba, V., Cote, G.L. 2003. Trichoderma reesei acetyl esterase catalyzed transesterification in water [abstract]. 6th International Symposium on Biocatalysis and Biotransformations, Olomouc, Czech Republic, Chem Listing 97:443. Technical Abstract: Hydrolases are a group of enzymes catalyzing hydrolytic reactions. Introduction of organic reaction media has made it possible to use these enzymes efficiently for reversed hydrolytic reactions and transferase-type reactions as well. Water in these organic systems is often believed to shift equilibrium in favor to hydrolysis. Although numerous studies show that minimizing water content is essential in such reactions, we found that partially purified Trichoderma reesei acetyl esterase was able to catalyze acyl transfer reactions not only in organic solvents and mixtures of organic solvents with water, but even in water alone. Using different acyl donors, the best results were obtained using vinyl acetate. As acetyl acceptors, a variety of hydroxyl bearing compounds in their water solutions was used. Conversion and number of newly formed acetates varied according to acceptor used. Conversions over 50% were observed by majority of most common monosaccharides, their methyl and deoxy derivatives, sugar alcohols, and oligosaccharides. In several cases, the transesterification was highly regioselective, leading to only one acetyl derivative. The preparative potential of these transesterifications in water was demonstrated by transacetylation of methyl beta-D-glucopyranoside and p-nitrophenyl beta-D-glucopyranoside, yielding 56.4% of methyl-3O-acetyl beta-D-glucopyranoside and 70.2% p-nitrophenyl 3-O-acetyl beta-D-glucopyranoside as the only products of the reactions. This new enzymatically catalyzed transacetylation in water opens a new area in chemoenzymatic synthesis. Its major advantages are simple and regioselective esterification of polar compounds in high yields, with low enzyme consumption, and most importantly, elimination of the use of toxic organic solvents.