Development of user-friendly, high throughput screening for ligands and inhibitors of carbohydrate modifying enzymes

This paper describes the impact of cloud computing and the use of GPUs on the performance of Autodock and Gromacs respectively. Cloud computing was applicable to reducing the ‘‘tail’’ seen in running Autodock on desktop grids and the GPU version of Gromacs showed significant improvement over the CPU version. A large (200,000 compounds) library of small molecules, seven sialic acid analogues of the putative substrate and 8000 sugar molecules were converted into pdbqt format and used to interrogate the Trichomonas vaginalis neuraminidase using Autodock Vina. Good binding energy was noted for some of the small molecules (~-9 kcal/mol), but the sugars bound with affinity of less than -7.6 kcal/mol. The screening of the sugar library resulted in a ‘‘top hit’’ with a-2,3-sialyllacto-N-fucopentaose III, a derivative of the sialyl Lewisx structure and a known substrate of the enzyme. Indeed in the top 100 hits 8 were related to this structure. A comparison of Autodock Vina and Autodock 4.2 was made for the high affinity small molecules and in some cases the results were superimposable whereas in others, the match was less good. The validation of this work will require extensive ‘‘wet lab’’ work to determine the utility of the workflow in the prediction of potential enzyme inhibitors.

The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism

Increased intake of dietary carbohydrate that is fermented in the colon by the microbiota has been reported to decrease body weight, although the mechanism remains unclear. Here we use in vivo11C-acetate and PET-CT scanning to show that colonic acetate crosses the blood–brain barrier and is taken up by the brain. Intraperitoneal acetate results in appetite suppression and hypothalamic neuronal activation patterning. We also show that acetate administration is associated with activation of acetyl-CoA carboxylase and changes in the expression profiles of regulatory neuropeptides that favour appetite suppression. Furthermore, we demonstrate through 13C high-resolution magic-angle-spinning that 13C acetate from fermentation of 13C-labelled carbohydrate in the colon increases hypothalamic 13C acetate above baseline levels. Hypothalamic 13C acetate regionally increases the 13C labelling of the glutamate–glutamine and GABA neuroglial cycles, with hypothalamic 13C lactate reaching higher levels than the ‘remaining brain’. These observations suggest that acetate has a direct role in central appetite regulation.

Preterm nutritional intake and MRI phenotype at term age: a prospective observational study

Objective: To describe (1) the relationship between nutrition and the preterm-at-term infant phenotype, (2) phenotypic differences between preterm-at-term infants and healthy term born infants and (3) relationships between somatic and brain MRI outcomes. Design: Prospective observational study. Setting: UK tertiary neonatal unit. Participants: Preterm infants (<32 weeks gestation) (n=22) and healthy term infants (n=39) Main outcome measures: Preterm nutrient intake; total and regional adipose tissue (AT) depot volumes; brain volume and proximal cerebral arterial vessel tortuosity (CAVT) in preterm infants and in term infants. Results: Preterm nutrition was deficient in protein and high in carbohydrate and fat. Preterm nutrition was not related to AT volumes, brain volume or proximal CAVT score; a positive association was noted between human milk intake and proximal CAVT score (r=0.44, p=0.05). In comparison to term infants, preterm infants had increased total adiposity, comparable brain volumes and reduced proximal CAVT scores. There was a significant negative correlation between deep subcutaneous abdominal AT volume and brain volume in preterm infants (r=−0.58, p=0.01). Conclusions: Though there are significant phenotypic differences between preterm infants at term and term infants, preterm macronutrient intake does not appear to be a determinant. Our preliminary data suggest that (1) human milk may exert a beneficial effect on cerebral arterial vessel tortuosity and (2) there is a negative correlation between adiposity and brain volume in preterm infants at term. Further work is warranted to see if our findings can be replicated and to understand the causal mechanisms.

Enzymatic grafting: A novel approach to develop multifunctional materials of interest

Today more than 99% of plastics are petroleum-based because of the availability and cost of the raw material. The durability of disposed plastics contributes to the environmental problems as waste and their persistence in the environment causes deleterious effects on the ecosystem. Environmental pollution awareness and the demand for green technology have drawn considerable attention of both academia and industry into biodegradable polymers. In this regard green chemistry technology has the potential to provide solution to this issue. Enzymatic grafting has recently been the focus of green chemistry technologies due to the growing environmental concerns, legal restrictions, and increasing availability of scientific knowledge. Over the last several years, research covering various applications of robust enzymes like laccases and lipases has been increased rapidly, particularly in the field of polymer science, to graft multi-functional materials of interest. In principle, enzyme-assisted grafting may modify/impart a variety of functionalities to the grafted composites which individual materials fail to demonstrate on their own. The modified polymers through grafting have a bright future and their development is practically boundless. In the present study series of graft composites with poly(3-hydroxybutyrate) (P(3HB) as side chain and cellulose as a backbone polymer were successfully synthesised by introducing enzymatic grafting technique where laccase and lipase were used as model catalysts [1-3]. Subsequently, the resulting composites were removed from the casting surface under ambient environment and characterised by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) in detail. Moreover, the thermo-mechanical behaviours of the grafted composites were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analyser (DMA) measurements, respectively. In addition, hydrophobic and hydrophilic characteristics of the grafted polymers were studied through drop contour analysis using water contact angle (WCA). In comparison to the individual counterparts improvement was observed in the thermo- mechanical properties of the composites to varied extent. The tensile strength, elongation at break, and Young’s modulus values of the composites reached their highest levels in comparison to the films prepared with pure P(3HB) only which was too fragile to measure any of the above said characteristics. Interestingly, untreated P(3HB) was hydrophobic in nature and after lipase treatment P(3HB) and P(3HB)-EC-based graft composite attained higher level of hydrophilicity. This is a desired characteristic that enhances the biocompatibility of the materials for proper cell adhesion and proliferation therefore suggesting potential candidates for tissue engineering/bio-medical type applications [3]. The present research will be a first step in the biopolymer modification. To date no report has been found in literature explaining the laccase/lipase assisted grafting of P(3HB) [1-3]. The newly grafted composites exhibit unique functionalities with wider range of potential applications in bio-plastics, pharmaceutical, and cosmetics industries, tissue engineering, and biosensors. [1] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Cellulose 21, 3613-3621 (2014). [2] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Carbohydrate Polymers 113, 131-137 (2014). [3] H.M.N. Iqbal, G. Kyazze, T. Tron and T. Keshavarz, Polymer Chemistry In-Press, DOI: 10.1039/C4PY0 0857J (2014).