Direct enzymatic esterification of cotton and Avicel with wild-type and engineered cutinases

In this work, the surface of cellulose, either Avicel or cotton fabric, was modified using cutinases without any previous treatment to swell or to solubilise the polymer. Aiming further improvement of cutinase ester synthase activity on cellulose, an engineered cutinase was investigated. Wild-type cutinase from Fusarium solani and its fusion with the carbohydrate-binding module N1 from Cellulomonas fimi were able to esterify the hydroxyl groups of cellulose with distinct efficiencies depending on the acid substrate/solvent system used, as shown by titration and by ATR-FTIR. The carbonyl stretching peak area increased significantly after enzymatic treatment during 72 h at 30 °C. Cutinase treatment resulted in relative increases of 31 and 9 % when octanoic acid and vegetable oil were used as substrates, respectively. Cutinase-N1 treatment resulted in relative increases of 11 and 29 % in the peak area when octanoic acid and vegetable oil were used as substrates, respectively. The production and application of cutinase fused with the domain N1 as a cellulose ester synthase, here reported for the first time, is therefore an interesting strategy to pursuit.This work was co-funded by the European Social Fund through the management authority POPH and FCT, Postdoctoral fellowship reference: SFRH/BPD/47555/2008. The authors also want to thank Doctor Raul Machado for his valuable help on FTIR spectral data treatment

Carboxylic ester hydrolases from hyperthermophiles

Carboxylic ester hydrolyzing enzymes constitute a large group of enzymes that are able to catalyze the hydrolysis, synthesis or transesterification of an ester bond. They can be found in all three domains of life, including the group of hyperthermophilic bacteria and archaea. Esterases from the latter group often exhibit a high intrinsic stability, which makes them of interest them for various biotechnological applications. In this review, we aim to give an overview of all characterized carboxylic ester hydrolases from hyperthermophilic microorganisms and provide details on their substrate specificity, kinetics, optimal catalytic conditions, and stability. Approaches for the discovery of new carboxylic ester hydrolases are described. Special attention is given to the currently characterized hyperthermophilic enzymes with respect to their biochemical properties, 3D structure, and classification

An Integrated Biorefinery Concept for Conversion of Sugar Beet Pulp into Value-added Chemicals and Pharmaceutical Intermediates

Over 8 million tonnes of sugar beet are grown annually in the UK. Sugar beet pulp (SBP) is the main by-product of sugar beet processing which is currently dried and sold as a low value animal feed. SBP is a rich source of carbohydrates, mainly in the form of cellulose and pectin, including D-glucose (Glu), L-arabinose (Ara) and D-galacturonic acid (GalAc). This work describes the technical feasibility of an integrated biorefinery concept for fractionation of SBP and conversion of these monosaccharides into value-added products. SBP fractionation is initially carried out by steam explosion under mild conditions to yield soluble pectin and insoluble cellulose fractions. The cellulose is readily hydrolysed by cellulases to release Glu that can then be fermented by a commercial Yeast strain to produce bioethanol with a high yield. The pectin fraction can be either fully hydrolysed, using physico-chemical methods, or selectively hydrolysed, using cloned arabinases and galacturonases, to yield Ara-rich and GalAc-rich streams. These monomers can be separated using either Centrifugal Partition Chromatography (CPC) or ultrafiltration into streams suitable for subsequent enzymatic upgrading. Building on our previous experience with transketolase (TK) and transaminase (TAm) enzymes, the conversion of Ara and GalAc into higher value products was explored. In particular the conversion of Ara into L-gluco-heptulose (GluHep), that has potential therapeutic applications in hypoglycaemia and cancer, using a mutant TK is described. Preliminary studies with TAm also suggest GluHep can be selectively aminated to the corresponding chiral aminopolyol. Current work is addressing upgrading of the remaining SBP monomer, GalAc, and modelling of the biorefinery concept to enable economic and Life Cycle Analysis (LCA)

Narcissism: a factor behind the selective sharing of news online

The current study examined the extent to which narcissism influences the social network users’ intention to share positive and negative life events with (close or unknown) online contacts. Using an online survey, small vignettes and a cross-sectional convenience sample of 119 participants, the results showed that narcissism positively predicted sharing intention of positive and negative life events with strangers. However, individuals rating higher in narcissism were less likely to share negative news with family. The research findings suggest that personality traits such as narcissism, the type of contacts online, and the nature of the news may shape what information is shared by online users. The type of news presented may therefore be a function of who is posting the content, their personality, and the kind of social network contacts they have online

A thermodynamic study of ketoreductase-catalyzed reactions 3. Reduction of 1-phenyl-1-alkanones in non-aqueous solvents

The equilibrium constants K for the reactions (1-phenyl-1-alkanone + 2-propanol = 1-phenyl-1-alkanol + acetone) in the solvents n-pentane and n-hexane have been determined by using gas chromatography at the temperature 298.15 K. The 1-phenyl-1-alkaones included in this study were: 1-phenyl-1-ethanone, 1-phenyl-1-propanone, 1-phenyl-1-butanone, 1-phenyl-1-pentanone, 1-phenyl-1-hexanone, and 1-phenyl-1-heptanone. The equilibrium constants for the reaction involving 1-phenyl-1-ethanone were measured in the solvent n-hexane as a function of temperature (288 K to 308 K). The calculated thermodynamic quantities for the 1-phenyl-1-ethanone reaction at T = 298.15 K are: K = 0.2177 ± 0.0018; the standard molar Gibbs free energy change, ∆rGmo=(3.78±0.02)kJ·mol-1, the standard molar enthalpy change, ∆rHmo=(4.53±0.87)kJ·mol-1, and the standard molar entropy change, ∆rSmo=(2.5±2.9)J·K-1·mol-1. The equilibrium constants of 1-phenyl-1-alkanone with an odd number of carbons in alkyl side chain are higher than the equilibrium constants of the preceding 1-phenyl-1-alkanone having an even number of carbons in the side chain and follow a zig-zag pattern with increasing carbon number in the alkyl side chain.© Elsevie

Executive function differences as a function of parent‐reported binge eating and weight: Results from the adolescent brain cognitive development study

Abstract Background Binge eating is a relatively common disordered eating behavior among children, and is associated with poor health outcomes. Executive function (EF)—higher order cognitive abilities related to planning and impulse control—may be implicated in both binge eating and pediatric obesity. Although EF deficits are evident among individuals with obesity and/or binge eating, findings are mixed across the lifespan. Methods The present study examined differences in EF among children with varying weight statuses and parent‐reported binge eating. The sample included 10,017 children from the Adolescent Brain Cognitive Development study, aged 9–10 years. Results Children with parent‐reported binge eating—either with overweight/obesity or normal weight—had significantly lower EF than those with no binge eating and a normal weight status but did not differ from those with no binge eating and overweight/obesity. Children with no binge eating and overweight/obesity also had statistically significantly lower EF than those with normal weight status. Although all significant differences between groups were negligible to very small, results may indicate similar neurocognitive profiles among children with binge eating and those with overweight/obesity. Conclusions Alterations in EF among children with binge eating may not be solely related to weight‐specific factors, as significant differences also emerged among children with normal weight status, with versus without parent‐reported binge eating. Future research is needed to understand temporal associations between obesity, disordered eating, and neurocognition in children using multi‐informant methods for assessing binge eating