1.Synthesis and emulsifying properties of carbohydrate fatty acid esters produced from Agave tequilana fructans by enzymatic acylation.
Casas-Godoy L1, Arrizon J1, Arrieta-Baez D2, Plou FJ3, Sandoval G4. Food Chem. 2016 Aug 1;204:437-43. doi: 10.1016/j.foodchem.2016.02.153. Epub 2016 Mar 2.
Carbohydrate fatty acid esters are non-ionic surfactants with a broad spectrum of applications. These molecules are generally synthesized using short carbohydrates or linear fructans; however in this research carbohydrate fatty acid esters were produced for the first time with branched fructans from Agave tequilana. Using immobilized lipases we successfully acylated A. tequilana fructans with vinyl laurate, obtaining products with different degrees of polymerization (DP). Lipozyme 435 was the most efficient lipase to catalyze the transesterification reaction. HPLC and ESI-MS analysis proved the presence of a mixture of acylated products as a result of the chemical complexity of fructans in the A. tequilana. The ESI-MS spectra showed a molecular mass shift between 183 and 366g/mol for fructooligosaccharides with a DP lower than 6, which indicated the presence of Agave fructans that had been mono- and diacylated with lauric acid. The carbohydrate fatty acid esters (CFAE) obtained showed good emulsifying properties in W/O emulsions.
2.Functional analysis of the binding model of microbial inulinases using docking and molecular dynamics simulation.
Singh PK1, Joseph J1, Goyal S2, Grover A2, Shukla P3. J Mol Model. 2016 Apr;22(4):69. doi: 10.1007/s00894-016-2935-y. Epub 2016 Mar 8.
Recently inulinase has regained interest due to its usage in the production of fructooligosaccharides, biofuels, and in pharmaceutical industries. Inulinases properties are experimentally reported by nomerous studies but their characteristics are just partially explained by only a few computational investigations. In the present study we have investigated exoinulinase and endoinulinase from different microbial sources toward their catalytic activity. Docking and molecular dynamic (MD) simulation were carried out for microbial endoinulinase and exoinulinase docked with 1-kestose and fructose-6-phosphate respectively. Pseudomonas mucidolens (-7.42 kcal mol(-1) binding energy), docked with fructose-6-phosphate, was recorded as the most favorable binding energy, Pseudomonas mucidolens made hydrogen bonds with fructose-6-phosphate and the amino acids involved were arginine 286, tryptophan 158, and isoleucine 87. After the simulation only tryptophan 158 remained bonded and additionally valine 156 made hydrogen bonds with fructose-6-phosphate.
3.High night temperature strongly impacts TCA cycle, amino acid and polyamine biosynthetic pathways in rice in a sensitivity-dependent manner.
Glaubitz U1, Erban A1, Kopka J1, Hincha DK1, Zuther E2. J Exp Bot. 2015 Oct;66(20):6385-97. doi: 10.1093/jxb/erv352. Epub 2015 Jul 23.
Global climate change combined with asymmetric warming can have detrimental effects on the yield of crop plants such as rice (Oryza sativa L.). Little is known about metabolic responses of rice to high night temperature (HNT) conditions. Twelve cultivars with different HNT sensitivity were used to investigate metabolic changes in the vegetative stage under HNT compared to control conditions. Central metabolism, especially TCA cycle and amino acid biosynthesis, were strongly affected particularly in sensitive cultivars. Levels of several metabolites were correlated with HNT sensitivity. Furthermore, pool sizes of some metabolites negatively correlated with HNT sensitivity under control conditions, indicating metabolic pre-adaptation in tolerant cultivars. The polyamines putrescine, spermidine and spermine showed increased abundance in sensitive cultivars under HNT conditions. Correlations between the content of polyamines and 75 other metabolites indicated metabolic shifts from correlations with sugar-phosphates and 1-kestose under control to correlations with sugars and amino and organic acids under HNT conditions.
4.Kinetics and model development for enzymatic synthesis of fructo-oligosaccharides using fructosyltransferase.
Kashyap R1, Palai T2, Bhattacharya PK3. Bioprocess Biosyst Eng. 2015 Dec;38(12):2417-26. doi: 10.1007/s00449-015-1478-4. Epub 2015 Oct 5.
Experimental investigations were made to synthesize fructo-oligosaccharides (FOS) from sucrose using fructosyltransferase. The influence of various parameters such as temperature (45-55 °C), pH (4-5), initial sucrose concentration (ISC: 300-500 g/L) and enzyme concentration (4-32 U/mL) were varied. A maximum FOS yield of 60% was observed at ISC 500 g/L, pH 4.5 with enzyme activity 32 U/mL and at 55 °C. It was confirmed that 1-kestose (tri-) was the major product of FOS as compared to nystose (tetra-) and fructosylnystose (penta-saccharides). Further, the reaction rate increases with increase in temperature. From separate sets of experiments, it was observed that FOS formation was affected by glucose inhibition. Apart from the increase in the rate of FOS formation with increasing enzyme activity, the final values of FOS yield increase though till 16 U/mL and thereafter attain plateau. A kinetic model was also developed, based on Michaelis-Menten kinetics, and a five-step ten-parameter model, including glucose inhibition, was obtained.