Efficient glucosylation of flavonoids by organic solvent-tolerant Staphylococcus saprophyticus CQ16 in aqueous hydrophilic media

A Novel Formononetin Derivative Promotes Anti-ischemic Effects on Acute Ischemic Injury in Mice

Natural flavonoids, formononetin and ononin, possess antioxidant, antibacterial, anti-inflammatory and neuroprotective effects. Many complications caused by SARS-CoV-2 make patients difficult to recover. Flavonoids, especially formononetin and ononin, have the potential to treat SARS-CoV-2 and improve myocardial injury. However, their poor water solubility, poor oral absorption, high toxicity, and high-cost purification limit industrial practical application. Succinylation modification provides a solution for the above problems. Formononetin-7-O-β-(6″-O-succinyl)-D-glucoside (FMP), a new compound, was succinyl glycosylated from formononetin by the organic solvent tolerant bacteria Bacillus amyloliquefaciens FJ18 in a 10.0% DMSO (v/v) system. The water solubility of the new compound was improved by over 106 times compared with formononetin, which perfectly promoted the application of formononetin and ononin. The conversion rate of formononetin (0.5 g/L) was almost 94.2% at 24 h, while the yield of formononetin-7-O-β-(6″-O-succinyl)-D-glucoside could achieve 97.2%. In the isoproterenol (ISO)-induced acute ischemia mice model, the myocardial injury was significantly improved with a high dose (40 mg/kg) of formononetin-7-O-β-(6″-O-succinyl)-D-glucoside. The lactate dehydrogenase level was decreased, and the catalase and superoxide dismutase levels were increased after formononetin-7-O-β-(6″-O-succinyl)-D-glucoside treatment. Thus, formononetin-7-O-β-(6″-O-succinyl)-D-glucoside has high water solubility, low toxicity, and shows significant antimyocardial ischemia effects.

A thermostable glycosyltransferase from Paenibacillus polymyxa NJPI29: recombinant expression, characterization, and application in synthesis of glycosides

Glycosylation is a prominent biological mechanism, affecting the structural and functional diversity of many natural products. In this study, a novel thermostable uridine diphosphate-dependent glycosyltransferase gene PpGT1 was cloned from Paenibacillus polymyxa NJPI29 and recombinantly expressed in B. subtilis WB600. The purified PpGT1 had a molecular weight of 45 kDa, as estimated using SDS-PAGE. The PpGT1 could catalyze the glycosylation of vanillic acid, methyl vanillate, caffeic acid, cinnamic alcohol, and ferulic acid. Moreover, PpGT1 possessed good thermostability and retained 80% of its original activity even after 12 h of incubation at 45 °C. In addition, PpGT1 remained stable within a neutral to alkaline pH range as well as in the presence of metal ions. The synthesis of methyl vanillate 4-O-β-D-glucoside by purified PpGT1 reached a yield 3.58 mM in a system with pH 8.0, 45 °C, 12 mM UDP-Glc, and 4 mM methyl vanillate. 3D-structure-based amino acid sequence alignments revealed that the catalytic residues and C-terminated PSPG motif were conserved. These unusual properties indicated that PpGT1 is a candidate UGT for valuable natural product industrial applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02855-z.

Glycosyl hydrolase catalyzed glycosylation in unconventional media

The reversible hydrolytic property of glycosyl hydrolases (GHs) as well as their acceptance of aglycones other than water has provided the abilities of GHs in synthesizing glycosides. Together with desirable physiochemical properties of glycosides and their high commercial values, research interests have been aroused to investigate the synthetic other than the hydrolytic properties of GHs. On the other hand, just like the esterification processes catalyzed by lipases, GH synthetic effectiveness is strongly obstructed by water both thermodynamically and kinetically. Medium engineering by involving organic solvents can be a viable approach to alleviate the obstacles caused by water. However, as native hydrolyases function in water-enriched environments, most GHs display poor catalytic performance in the presence of organic solvents. Some GHs from thermophiles are more tolerant to organic solvents due to their robust folded structures with strong residue interactions. Other than native sources, immobilization, protein engineering, employment of surfactant, and lyophilization have been proved to enhance the GH stability from the native state, which opens up the possibilities for GHs to be employed in unconventional media as synthases. KEY POINTS: • Unconventional media enhance the synthetic ability but destabilize GHs. • Viable approaches are discussed to improve GH stability from the native state. • GHs robust in unconventional media can be valuable industrial synthases.

Biochemical characterization of an organic solvent-tolerant glycosyltransferase from Bacillus licheniformis PI15 with potential application for raspberry ketone glycoside production

Raspberry ketone is a primary aroma component of the red raspberry. The glycosylation of this compound is a potential approach used to improve its pharmaceutical properties. In this work, raspberry ketone glycosides are produced in bacteria for the first time. Bacillus licheniformis PI15, an organic solvent-tolerant glycosyltransferase-producing strain, was isolated from chemically polluted soil. The cloning and heterologous expression of a glycosyltransferase, which was designated PI-GT1, in Escherichia coli BL21 resulted in the expression of an active and soluble protein that accounted for 15% of the total cell protein content. Purified PI-GT1 was highly active and stable over a broad pH range (6.0-10.0) and showed excellent pH stability. PI-GT1 maintained almost 60% of its maximal activity after 3 H of incubation at 20-40 °C and demonstrated optimal activity at 30 °C. Additionally, PI-GT1 displayed high stability and activity in the presence of hydrophilic solvents with log P ≤ -0.2 and retained more than 80% of its activity after 3 H of treatment. Supplementation with 10% DMSO markedly improved the glycosylation of raspberry ketone, resulting in a value 26 times higher than that in aqueous solution. The organic solvent-tolerant PI-GT1 may have potential uses in industrial chemical and pharmaceutical synthesis applications.

Ca2+ assisted glycosylation of phenolic compounds by phenolic-UDP-glycosyltransferase from Bacillus subtilis PI18

A phenolic-UDP-glycosyltransferase Bs-PUGT from Bacillus subtilis PI18 was cloned and expressed in Escherichia coli BL21 (DE3). The purified Bs-PUGT could catalyze the glycosylation of tyrosol, 4-hydroxybenzyl alcohol, 2-hydroxybenzyl alcohol, caffeic acid, cinnamic alcohol, ferulic acid, and so on. This enzyme showed a high activity and stability over a broad pH range and was sensitive to temperature. Studies on the kinetic parameters indicated that the affinity of Bs-PUGT to UDP-G (Km) and its catalytic efficiency (Kcat) increased by 1.5-fold and 1.7-fold, respectively, with the addition of 10 mM Ca²⁺. The most effective glycosylation of caffeic acid catalyzed by whole-cell E. coli/Bs-PUGT was achieved with a molar yield of 78.3% in a system with pH 8.0, 30 °C, 25 g/L sucrose, 10 mM Ca²⁺, and 0.5 g/L substrate concentration. The addition of Ca²⁺ increased the molar yield of caffeic acid glucosides and shortened the reaction. This work proposes a strategy for the efficient glycosylation of phenolic compounds by microbe-derived glycosyltransferase assisted by metal ions.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014

This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.

Enzymatic synthesis of isomaltotriose palmitate and evaluation of its emulsifying property

Enzymatic syntheses of oligosaccharide fatty acid esters are important owing to their wide range of industrial applications in the food, cosmetic, and pharmaceutical industries. Transesterification of isomaltotriose and palmitic acid vinyl ester, catalyzed by the metalloprotease thermolysin, was performed in organic solvents. The process parameters (reaction time and temperature) were optimized to achieve the highest yield of isomaltotriose palmitate (IP). The water content of the reaction system played a key role in the acylation of isomaltotriose. Dimethyl sulfoxide was thought to be the most suitable reaction medium by taking the degree of substitution of the modified isomaltotriose into account. The optimum reaction time, temperature, water content, and enzyme concentration were 24h, 45°C, 40%, and 0.05%, respectively, under which the product yield was as high as 89.7%. The enzyme operational stability study showed that thermolysin retained 51.5% of its initial activity for the synthesis of IP (even after repeated use for 72h). Moreover, test results showed that the emulsifying capacity and emulsion stability of IP are 107.5mL oil/g ester and 16.3%, respectively.

Microbial Glycosylation of Daidzein, Genistein and Biochanin A: Two New Glucosides of Biochanin A

Biotransformation of daidzein, genistein and biochanin A by three selected filamentous fungi was investigated. As a result of biotransformations, six glycosylation products were obtained. Fungus Beauveria bassiana converted all tested isoflavones to 4″-O-methyl-7-O-glucosyl derivatives, whereas Absidia coerulea and Absidia glauca were able to transform genistein and biochanin A to genistin and sissotrin, respectively. In the culture of Absidia coerulea, in addition to the sissotrin, the product of glucosylation at position 5 was formed. Two of the obtained compounds have not been published so far: 4″-O-methyl-7-O-glucosyl biochanin A and 5-O-glucosyl biochanin A (isosissotrin). Biotransformation products were obtained with 22%–40% isolated yield.

Precisely regulated galactosylation of nucleoside analogues in aqueous hydrophilic solvents catalyzed by solvent-stable β-galactosidase

Precisely regulated galactosylation of nucleoside analogues by the addition of aqueous hydrophilic solvents.