Biosynthesis of glyceride glycoside (nonionic surfactant) by amylosucrase,a powerful glycosyltransferase

Amylosucrase (ASase, E.C. 2.4.1.4) is a powerful transglycosylation enzyme that can transfer glucose from sucrose to the hydroxyl (-OH) group of various compounds. In this study, recombinant ASases from Deinococcus geothermalis (DgAS) and Bifidobacterium thermophilum (BtAS) were used to synthesize biosurfactants based on the computational analysis of predicted docking simulations. Successful predictions of the binding affinities, conformations, and three-dimensional structures of three surfactants were computed from receptor-ligand binding modes. DgAS and BtAS were effective in the synthesis of biosurfactants from glyceryl caprylate, glyceryl caprate, and polyglyceryl-2 caprate. The results of the transglycosylation reaction were consistent for both ASases, with glyceryl caprylate acceptor showing the highest concentration, as confirmed by thin layer chromatography. Furthermore, the transglycosylation reactions of DgAS were more effective than those of BtAS. Among the three substrates, glyceryl caprylate glycoside and glyceryl caprate glycoside were successfully purified by liquid chromatography–mass spectrometry (LC–MS) with the corresponding molecular weights.     

Electrochemical studies of the nickel catecholate complexes for detection of sulphur dioxide gas

Nickel catecholate complexes, bis(diphenylphosphino)ethanenickelcatecholate [(dppe)NiO₂C₆H₃4-R₁] R₁ = CH₃ (1), C(CH₃)₃ (2), H (3) and F (4)] were studied using CV and SWV techniques between −1.5 and +1.5 V at 50 mV s⁻¹ in cathodic and anodic sweeps. Glassy carbon electrode was used with 0.1 M tetrabutylammonium tetrafluroborate (TBATFB) in CH₂Cl₂. Complexes 1-4 before addition of SO₂, showed approximately reversible behaviour (i_pa/i_pc ≈ 1 and ΔE ≈ 77-88 mV); oxidation peaks observed between +313 and +524 mV, reduction peaks between +225 and +436 mV, depending on the substituent on the ligand. Detection limit 0.01 ppm, linear range 0.01-20 ppm, sensitivity 0.02 ppm/mV (with SWV) were obtained. The complexes 1 and 2 could be used as voltammetric sensors while complexes 3 and 4 would be suitable as amperometric sensors, for monitoring industrial SO₂ emissions.     

Whole-cell bioconversion using non-Leloir transglycosylation reactions: a review

Food Science and Biotechnology - Microbial biocatalysts are evolving technological tools for glycosylation research in food, feed and pharmaceuticals. Advances in bioengineered Leloir and...