- Engineering faster transglycosidases and their acceptor specificity
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Transglycosidases are enzymes that have the potential to catalyze the synthesis of a wide range of high-value compounds starting from biomass-derived feedstocks. Improving their activity and broadening the substrate range are important goals to enable the widespread application of this family of biocatalysts. In this work, we engineered 20 mutants of the rice transglycosidase Os9BGlu31 and evaluated their catalysis in 462 reactions over 18 different substrates. This allowed us to identify mutants that expanded their substrate range and showed high activity, including W243L and W243N. We also developed double mutants that show very high activity on certain substrates and exceptional specificity towards hydrolysis, such as L241D/W243N. In order to guide a more general use of Os9BGlu31 variants as transglycosylation catalysts, we built cheminformatics models based on topological descriptors of the substrates. These models showed useful predictive potential on the external validation set and are allowing the identification of efficient catalytic routes to novel phytohormone and antibiotic glucoconjugates of interest.
- Tran, Linh T.,Blay, Vincent,Luang, Sukanya,Eurtivong, Chatchakorn,Choknud, Sunaree,González-Diáz, Humbert,Ketudat Cairns, James R.
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supporting information
p. 2823 - 2836
(2019/06/13)
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- Hydroxycinnamoyl Glucose and Tartrate Esters and Their Role in the Formation of Ethylphenols in Wine
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Synthesized p-coumaroyl and feruloyl l-tartrate esters were submitted to Brettanomyces bruxellensis strains AWRI 1499, AWRI 1608, and AWRI 1613 to assess their role as precursors to ethylphenols in wine. No evolution of ethylphenols was observed. Additionally, p-coumaroyl and feruloyl glucose were synthesized and submitted to B. bruxellensis AWRI 1499, which yielded both 4-ethylphenol and 4-ethylguaiacol. Unexpected chemical transformations of the hydroxycinnamoyl glucose esters during preparation were investigated to prevent these in subsequent synthetic attempts. Photoisomerization gave an isomeric mixture containing the trans-esters and undesired cis-esters, and acyl migration resulted in a mixture of the desired 1-O-β-ester and two additional migrated forms, the 2-O-α- and 6-O-α-esters. Theoretical studies indicated that the photoisomerization was facilitated by deprotonation of the phenol, and acyl migration is favored during acidic, nonaqueous handling. Preliminary LC-MS/MS studies observed the migrated hydroxycinnamoyl glucose esters in wine and allowed for identification of feruloyl glucose in red wine for the first time.
- Hixson, Josh L.,Hayasaka, Yoji,Curtin, Christopher D.,Sefton, Mark A.,Taylor, Dennis K.
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p. 9401 - 9411
(2016/12/23)
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- Biotransformation of phenylcarboxylic acids by plant cell cultures
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A suspension culture of Glycyrrhiza echinata converted benzoic acid into its glucosyl ester. Suspension cultures of Aconitum japonicum, Coffea arabica, Dioscoreophyllum cumminsii and Nicotiana tabacum, transformed benzoic acid into its gentiobiosyl ester in addition to the glucosyl ester. The suspension cultures of A.japonicum and G. echinata converted phenylacetic acid into the esters attached to the C-6 position of glucose, that is, 6-O-phenylacetyl-d-glucose and ethyl 6-O-phenylacetyl-β-d-glucopyranoside. That of D. cumminsii converted phenylacetic acid into the glucose ester and also into phenethyl β-d-glucopyranoside showing glucosylation after the reduction of the carboxylic group. These suspension cultures converted cinnamic acid into p-coumaric acid and its glucosyl ester and p-coumaric acid into its glucosyl ester. However, the conversion of caffeic acid was not observed. The suspension cultures of A.japonicum and C. arabica converted 3-phenylpropionic acid into its gentiobiosyl ester. On the other hand, the culture of D. cumminsii did not produce the glycosyl ester but instead 3-(4-hydroxyphenyl)propionic acid was formed, thus showing hydroxylation capability.
- Ushiyama, Masashi,Kumagai, Shigehiro,Furuya, Tsutomu
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p. 3335 - 3339
(2007/10/02)
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