Recent trends in synthetic enzymatic cascades promoted by alcohol dehydrogenases

Alcohol dehydrogenases have fascinated chemists over the span of a few decades to catalyze oxidation and reduction reactions and have been increasingly incorporated as bio- catalysts in scaled-up industrial processes for the production of valuable chiral compounds under mild and environmentally friendly conditions. In this review, we discuss recent advances on alcohol dehydrogenases coupled in cascade reactions with other enzyme classes, chemocatalysts, or organocatalysts to obtain high value–added products. The examples include deracemization processes for the synthesis of chiral diols and amino alcohols, whole-cell and co-expression systems, and chemoenzymatic and organoenzymatic cascades, with a vision for future developments

Intensification of precipitation extremes with warming in a cloud resolving model

A cloud-resolving model is used to investigate the effect of warming on high percentiles of precipitation (precipitation extremes) in the idealized setting of radiative-convective equilibrium. While this idealized setting does not allow for several factors that influence precipitation in the tropics, it does allow for an evaluation of the response of precipitation extremes to warming in simulations with resolved rather than parameterized convection. The methodology developed should also be applicable to less idealized simulations. Modeled precipitation extremes are found to increase in magnitude in response to an increase in sea surface temperature. A dry static energy budget is used to relate the changes in precipitation extremes to changes in atmospheric temperature, vertical velocity, and precipitation efficiency. To first order, the changes in precipitation extremes are captured by changes in the mean temperature structure of the atmosphere. Changes in vertical velocities play a secondary role and tend to weaken the strength of precipitation extremes, despite an intensification of updraft velocities in the upper troposphere. The influence of changes in condensate transports on precipitation extremes is quantified in terms of a precipitation efficiency; it does not change greatly with warming. Tropical precipitation extremes have previously been found to increase at a greater fractional rate than the amount of atmospheric water vapor in observations of present-day variability and in some climate model simulations with parameterized convection. But the fractional increases in precipitation extremes in the cloud-resolving simulations are comparable in magnitude to those in surface water vapor concentrations (owing to a partial cancellation between dynamical and thermodynamical changes), and are substantially less than the fractional increases in column water vapor.Texas Advanced Computing CenterNational Science Foundation (U.S.) (TeraGrid resources

A Tailor-Made Deazaflavin-Mediated Recycling System for Artificial Nicotinamide Cofactor Biomimetics

[Image: see text] Nicotinamide adenine dinucleotide (NAD) and its 2′-phosphorylated form NADP are crucial cofactors for a large array of biocatalytically important redox enzymes. Their high cost and relatively poor stability, however, make them less attractive electron mediators for industrial processes. Nicotinamide cofactor biomimetics (NCBs) are easily synthesized, are inexpensive, and are also generally more stable than their natural counterparts. A bottleneck for the application of these artificial hydride carriers is the lack of efficient cofactor recycling methods. Therefore, we engineered the thermostable F(420):NADPH oxidoreductase from Thermobifida fusca (Tfu-FNO), by structure-inspired site-directed mutagenesis, to accommodate the unnatural N1 substituents of eight NCBs. The extraordinarily low redox potential of the natural cofactor F(420)H(2) was then exploited to reduce these NCBs. Wild-type enzyme had detectable activity toward all selected NCBs, with K(m) values in the millimolar range and k(cat) values ranging from 0.09 to 1.4 min(–1). Saturation mutagenesis at positions Gly-29 and Pro-89 resulted in mutants with up to 139 times higher catalytic efficiencies. Mutant G29W showed a k(cat) value of 4.2 s(–1) toward 1-benzyl-3-acetylpyridine (BAP(+)), which is similar to the k(cat) value for the natural substrate NADP(+). The best Tfu-FNO variants for a specific NCB were then used for the recycling of catalytic amounts of these nicotinamides in conversion experiments with the thermostable ene-reductase from Thermus scotoductus (TsOYE). We were able to fully convert 10 mM ketoisophorone with BAP(+) within 16 h, using F(420) or its artificial biomimetic FOP (FO-2′-phosphate) as an efficient electron mediator and glucose-6-phosphate as an electron donor. The generated toolbox of thermostable and NCB-dependent Tfu-FNO variants offers powerful cofactor regeneration biocatalysts for the reduction of several artificial nicotinamide biomimetics at both ambient and high temperatures. In fact, to our knowledge, this enzymatic method seems to be the best-performing NCB-recycling system for BNAH and BAPH thus far

Belimumab : a technological advance for systemic lupus erythematosus patients? Report of a systematic review and meta-analysis

Objectives: To undertake a systematic review and meta-analysis to investigate clinical effectiveness of belimumab for patients with systemic lupus erythematosus (SLE) and antinuclear and/or anti-double-stranded DNA (dsDNA) autoantibodies. Methods: We searched eight electronic databases and reference lists for randomised controlled trials (RCTs) of belimumab against placebo or best supportive care. Quality assessment and random effects meta-analysis were undertaken. Design: A meta-analysis of RCTs. Participants: 2133 SLE patients. Primary and secondary outcome measures: SLE Responder Index (SRI) at week 52. Results: Three double-blind placebo-controlled RCTs (L02, BLISS-52 BLISS-76) investigated 2133 SLE patients. BLISS-52 and BLISS-76 trials recruited patients with antinuclear and/or anti-dsDNA autoantibodies and demonstrated belimumab effectiveness for the SRI at week 52. Ethnicity and geographical location of participants varied considerably between BLISS trials. Although tests for statistical heterogeneity were negative, BLISS-52 results were systematically more favourable for all measured outcomes. Meta-analysis of pooled 52-week SRI BLISS results showed benefit for belimumab (OR 1.63, 95% CI 1.27 to 2.09). By week 76, the primary SRI outcome in BLISS-76 was not statistically significant (OR 1.31, 95% CI 0.919 to 1.855)

Hybrid catalysis for enantioselective Baeyer-Villiger oxidation and stereoselective epoxidation: a Cp*Ir complex to fuel FMN and FAD reduction for flavoprotein monooxygenase modules

Taking advantage of the unique properties of two-component flavo-monooxygenases and the ability of [Cp*Ir(bpy-OMe)H]+ to transfer hydrides to reduce flavins, we extended the scope of the pH- and oxygen-robust iridium(iii)-complex to drive the enzymatic reaction of a FMN-dependent Baeyer-Villiger monooxygenase and a FAD-dependent styrene monooxygenase (respectively FPMO Group C and E), using formic acid as H-donor for NADH recycling

A xylenol orange-based screening assay for the substrate specificity of flavin-dependent para-phenol oxidases

Vanillyl alcohol oxidase (VAO) and eugenol oxidase (EUGO) are flavin-dependent enzymes that catalyse the oxidation of para-substituted phenols. This makes them potentially interesting biocatalysts for the conversion of lignin-derived aromatic monomers to value-added compounds. To facilitate their biocatalytic exploitation, it is important to develop methods by which variants of the enzymes can be rapidly screened for increased activity towards substrates of interest. Here, we present the development of a screening assay for the substrate specificity of para-phenol oxidases based on the detection of hydrogen peroxide using the ferric-xylenol orange complex method. The assay was used to screen the activity of VAO and EUGO towards a set of twenty-four potential substrates. This led to the identification of 4-cyclopentylphenol as a new substrate of VAO and EUGO and 4-cyclohexylphenol as a new substrate of VAO. Screening of a small library of VAO and EUGO active-site variants for alterations in their substrate specificity led to the identification of a VAO variant (T457Q) with increased activity towards vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) and a EUGO variant (V436I) with increased activity towards chavicol (4-allylphenol) and 4-cyclopentylphenol. This assay provides a quick and efficient method to screen the substrate specificity of para-phenol oxidases, facilitating the enzyme engineering of known para-phenol oxidases and the evaluation of the substrate specificity of novel para-phenol oxidases

Can you tell your clunis from your cubitus? A benchmark for functional imaging

Advances in functional brain imaging have allowed the development of new investigative techniques with clinical application—ranging from presurgical mapping of eloquent cortex to identifying cortical regions involved in religious experiences. Similarly a variety of methods are available to referring physicians, ranging from metabolic measures such as functional magnetic resonance imaging and positron emission tomography to measurements based on electrical activity such as electroencephalography and magnetoencephalography. However, there are no universal benchmarks by which to judge between these methods. In this study we attempt to develop a standard for functional localisation, based on the known functional organisation of somatosensory cortex. Studies have shown spatially distinct sites of brain activity in response to stimulation of various body parts. Generally these studies have focused on areas with large cortical representations, such as the index finger and face. We tested the limits of magnetoencephalography source localisation by stimulation of body parts, namely the clunis and the cubitus, that map to proximal and relatively poorly represented regions of somatosensory cortex