Economics of Emerging Ammonia Fertilizer Production Methods - a Role for On-Farm Synthesis?

Prospects of recent promising methods of producing ammonia without fossil fuels are discussed. Despite demonstrating efficiency gains over previous similar approaches, the novel biological and electrochemical pathways require further large improvements to compete with electricity-powered Haber-Bosch. As some literature asserts that future production will shift to smaller scales, such as on-farm, we qualitatively discuss the economics of scale of future green ammonia production.

Insights into Nitrogenase Bioelectrocatalysis for Green Ammonia Production.

There is a growing interest in using ammonia as a liquid carrier of hydrogen for energy applications. Currently, ammonia is produced industrially by the Haber-Bosch process, which requires high temperature and high pressure. In contrast, bacteria have naturally evolved an enzyme known as nitrogenase, that is capable of producing ammonia and hydrogen at ambient temperature and pressure.

Engineering a solid-state metalloprotein hydrogen evolution catalyst.

Hydrogen has the potential to play an important role in decarbonising our energy systems. Crucial to achieving this is the ability to produce clean sources of hydrogen using renewable energy sources. Currently platinum is commonly used as a hydrogen evolution catalyst, however, the scarcity and expense of platinum is driving the need to develop non-platinum-based catalysts.

Enhancement of metallomacrocycle-based oxygen reduction catalysis through immobilization in a tunable silk-protein scaffold.

Fuel cells convert chemical energy into electrical current with the use of an oxidant such as oxygen and have the potential to reduce our reliance on fossil fuels. To overcome the slow kinetics of the oxygen reduction reaction (ORR), platinum is often used as the catalyst. However, the scarcity and expense of platinum limits the wide-spread use of fuel cells.

Biocompatibility and immunogenic response to recombinant honeybee silk material.

If tolerated in biological environments, recombinant structural proteins offer the advantage that biological cues dictating cell attachment and material degradation can be modified as required for clinical application using genetic engineering. In this study, we investigate the biological response to materials generated from the recombinant honeybee silk protein, AmelF3, a structural protein that can be produced at high levels by fermentation in Escherichia coli. The protein can be readily purified from E.

Confirmation of Bioinformatics Predictions of the Structural Domains in Honeybee Silk.

Honeybee larvae produce a silk made up of proteins in predominantly a coiled coil molecular structure. These proteins can be produced in recombinant systems, making them desirable templates for the design of advanced materials. However, the atomic level structure of these proteins is proving difficult to determine: firstly, because coiled coils are difficult to crystalize; and secondly, fibrous proteins crystalize as fibres rather than as discrete protein units.

FAD-sequestering proteins protect mycobacteria against hypoxic and oxidative stress.

The ability to persist in the absence of growth triggered by low oxygen levels is a critical process for the survival of mycobacterial species in many environmental niches. (), a gene of unknown function in , is up-regulated in response to hypoxia and regulated by DosRDosS/DosT, an oxygen- and redox-sensing two-component system that is highly conserved in mycobacteria. In this communication, we demonstrate that MSMEG_5243 is a lavin-uestering protein and henceforth refer to it as Fsq.

Did aculeate silk evolve as an antifouling material?

Many of the challenges we currently face as an advanced society have been solved in unique ways by biological systems. One such challenge is developing strategies to avoid microbial infection. Social aculeates (wasps, bees and ants) mitigate the risk of infection to their colonies using a wide range of adaptations and mechanisms.

Modification of Honeybee Silk by the Addition of Antimicrobial Agents.

Honeybee silk proteins can be produced at high levels in recombinant systems, fabricated into materials, and are tolerant of amino acid modifications: properties that make them exciting templates for designing new functional materials. Here, we explore the properties of materials either made from silk-antimicrobial peptide (AMP) fusion proteins or silk containing entrapped AMPs or silver nanoparticles. Inclusion of AMP within the silk protein sequence did not affect our ability to express the proteins or process them into films.

Silk provides a new avenue for third generation biosensors: Sensitive, selective and stable electrochemical detection of nitric oxide.

Using heme entrapped in recombinant silk films, we have produced 3rd generation biosensors, which allow direct electron transfer from the heme center to an electrode avoiding the need for electron mediators. Here, we demonstrate the use of these heme-silk films for the detection of nitric oxide (NO) at nanomolar levels in the presence and absence of oxygen. The sensor was prepared by drop-casting a silk solution on a glassy carbon electrode modified with multiwalled carbon nanotubes (MWCNT) followed by infusion with heme.

Rational design of new materials using recombinant structural proteins: Current state and future challenges.

Sequence-definable polymers are seen as a prerequisite for design of future materials, with many polymer scientists regarding such polymers as the holy grail of polymer science. Recombinant proteins are sequence-defined polymers. Proteins are dictated by DNA templates and therefore the sequence of amino acids in a protein is defined, and molecular biology provides tools that allow redesign of the DNA as required.

Design of silk proteins with increased heme binding capacity and fabrication of silk-heme materials.

In our previous studies, heme was bound into honeybee silk to generate materials that could function as nitric oxide sensors or as recoverable heterogeneous biocatalysts. In this study, we sought to increase the heme-binding capacity of the silk protein by firstly redesigning the heme binding site to contain histidine as the coordinating residue and secondly, by adding multiple histidine residues within the core of the coiled coil core region of the modified silk protein. We used detergent and a protein denaturant to confirm the importance of the helical structure of the silk for heme coordination.

Practice education facilitator roles and their value to NHS organisations.

The role of the practice education facilitator (PEF) was introduced to support the management of large student nurse numbers in clinical areas and to monitor and enhance the quality of placements. While much has been written about the activities and roles undertaken by PEFs, less is known about the value of this type of role to the NHS organisations that employ them. This article explores some of the views of PEFs working in a variety of trusts and organisations in London and surrounding counties.

Recombinant Structural Proteins and Their Use in Future Materials.

Recombinant proteins are polymers that offer the materials engineer absolute control over chain length and composition: key attributes required for design of advanced polymeric materials. Through this control, these polymers can be encoded to contain information that enables them to respond as the environment changes. However, despite their promise, protein-based materials are under-represented in materials science.

Solid-State Metalloproteins-An Alternative to Immobilisation.

This commentary outlines a protein engineering approach as an alternative to immobilisation developed in our laboratory. We use a recombinant silk protein into which metal active sites can be incorporated to produce solid-state metalloprotein materials. The silk protein directly coordinates to the metal centres providing control over their reactivity akin to that seen in naturally occurring metalloproteins.

De Novo Engineering of Solid-State Metalloproteins Using Recombinant Coiled-Coil Silk.

To achieve the sophisticated chemistry required for life, nature uses metal containing proteins (metalloproteins). However, despite intensive research efforts, very few of these metalloproteins have been exploited for biotechnological applications. One major limiting factor is the poor stability of these proteins when they are removed from their cellular environment.

Embracing external scrutiny to build bridges and genuine partnerships between education and clinical practice.

Despite having made significant changes and improvements since 2007, publication of The Mid-Staffordshire National Health Service Foundation Trust Public Inquiry (2013) refocused attention on the poor care standards that had taken place. Recommendations include far reaching national transformational changes not only for the National Health Service but also for professional regulatory bodies and other agencies linked to health and social care. This paper describes how external scrutiny was embraced to move staff from initial loss of confidence, feelings of anger and defensiveness to embracing opportunities to increase transparency, build bridges and genuine partnerships between universities and healthcare providers.

Micromolar biosensing of nitric oxide using myoglobin immobilized in a synthetic silk film.

In this work we investigate the use of coiled-coil silk proteins, produced in recombinant Escherichia coli, as a new material for immobilizing biosensors. Myoglobin was embedded in transparent honeybee silk protein films. Immobilized myoglobin maintained a high affinity for nitric oxide (KD NO=52 µM) and good sensitivity with a limit of detection of 5 µM.

The impact of operative approach for oesophageal cancer on outcome: the transhiatal approach may influence circumferential margin involvement.

Aim: Surgery for oesophageal cancer remains the only means of cure for invasive tumours. It is claimed that the surgical approach for these cancers impacts on morbidity and may influence the ability to achieve tumour clearance and therefore survival, however there is no conclusive evidence to support one approach over another. This study aims to determine the impact of operative approach on tumour margin involvement and survival.

Short circuiting a sulfite oxidising enzyme with direct electrochemistry: active site substitutions and their effect on catalysis and electron transfer.

Sulfite dehydrogenase (SDH) from Starkeya novella is a heterodimeric enzyme comprising a Mo active site and a heme c electron relay, which mediates electron transfer from the Mo cofactor to cytochrome c following sulfite oxidation. Studies on the wild type enzyme (SDH(WT)) and its variants have identified key amino acids at the active site, specifically Arg-55 and His-57. We report the Mo(VI/V), Mo(V/IV) and Fe(III/II) (heme) redox potentials of the variants SDH(R55K), SDH(R55M), SDH(R55Q) and SDH(H57A) in comparison with those of SDH(WT).

Pulsed EPR investigations of the Mo(V) centers of the R55Q and R55M variants of sulfite dehydrogenase from Starkeya novella.

Continuous-wave and pulsed electron paramagnetic resonance (EPR) spectroscopy have been used to characterize two variants of bacterial sulfite dehydrogenase (SDH) from Starkeya novella in which the conserved active-site arginine residue (R55) is replaced by a neutral amino acid residue. Substitution by the hydrophobic methionine residue (SDH(R55M)) has essentially no effect on the pH dependence of the EPR properties of the Mo(V) center, even though the X-ray structure of this variant shows that the methionine residue is rotated away from the Mo center and a sulfate anion is present in the active-site pocket (Bailey et al. in J Biol Chem 284:2053-2063, 2009).

Intramolecular electron transfer in sulfite-oxidizing enzymes: elucidating the role of a conserved active site arginine.

All reported sulfite-oxidizing enzymes have a conserved arginine in their active site which hydrogen bonds to the equatorial oxygen ligand on the Mo atom. Previous studies on the pathogenic R160Q mutant of human sulfite oxidase (HSO) have shown that Mo-heme intramolecular electron transfer (IET) is dramatically slowed when positive charge is lost at this position. To improve our understanding of the function that this conserved positively charged residue plays in IET, we have studied the equivalent uncharged substitutions R55Q and R55M as well as the positively charged substitution R55K in bacterial sulfite dehydrogenase (SDH).

Molecular basis for enzymatic sulfite oxidation: how three conserved active site residues shape enzyme activity.

Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis.

Direct catalytic electrochemistry of sulfite dehydrogenase: mechanistic insights and contrasts with related Mo enzymes.

Under hydrodynamic electrochemical conditions with slow cyclic voltammetry sweep rates we have been able to probe catalytic events at the molybdenum active site of sulfite dehydrogenase (SDH) from Starkeya novella adsorbed on an edge plane graphite electrode within a polylysine film. The electrochemically driven catalytic behaviour of SDH mirrors that seen in solution assays suggesting that the adsorbed enzyme retains its native activity. However, at high sulfite concentrations, the voltammetric waveform transforms from the expected sigmoidal profile to a peak-shaped response, similar to that reported for the molybdenum enzymes DMSO reductase and nitrate reductase (NarGHI and NapAB) where a redox reaction at the active site has been associated with a switch to lower activity at high overpotentials.