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ammonium borane

Maartje Ahj van Kessel, Karin Stultiens, Monique Fw Slegers, Simon Guerrero Cruz, Mike Sm Jetten, Boran Kartal, Huub Jm Op den Camp
The efficient treatment of wastewater for the removal of nitrogen is of key importance to prevent eutrophication and deoxygenation of receiving water bodies. In addition, ineffective wastewater treatment can be a source of greenhouse gasses. The application of newly discovered microbial processes, such as nitrite/nitrate-dependent methane oxidation (N-damo), can make wastewater treatment systems more sustainable; especially when they are combined with anaerobic ammonium oxidation (anammox). A treatment system based on these microbial processes will need oxygen supply for the production of nitrite...
April 2018: Current Opinion in Biotechnology
Yu Fang, Zhifeng Xiao, Jialuo Li, Christina Lollar, Lujia Liu, Xizhen Lian, Shuai Yuan, Sayan Banerjee, Peng Zhang, Hong-Cai Zhou
Earth-abundant first-row transition-metal nanoclusters (NCs) have been extensively investigated as catalysts. However, their catalytic activity is relatively low compared with noble metal NCs. Enhanced catalytic activity of cobalt NCs can be achieved by encapsulating Co NCs in soluble porous coordination cages (PCCs). Two cages, PCC-2a and 2b, possess almost identical cavity in shape and size, while PCC-2a has five times more net charges than PCC-2b. Co2+ cations were accumulated in PCC-2a and reduced to ultra-small Co NCs in situ, while for PCC-2b, only bulky Co particles were formed...
May 4, 2018: Angewandte Chemie
Marcel M M Kuypers, Hannah K Marchant, Boran Kartal
Nitrogen is an essential component of all living organisms and the main nutrient limiting life on our planet. By far, the largest inventory of freely accessible nitrogen is atmospheric dinitrogen, but most organisms rely on more bioavailable forms of nitrogen, such as ammonium and nitrate, for growth. The availability of these substrates depends on diverse nitrogen-transforming reactions that are carried out by complex networks of metabolically versatile microorganisms. In this Review, we summarize our current understanding of the microbial nitrogen-cycling network, including novel processes, their underlying biochemical pathways, the involved microorganisms, their environmental importance and industrial applications...
May 2018: Nature Reviews. Microbiology
Haamid R Bhat, Prakash C Jha
The anion binding selectivity and the recognition mechanism of two isomeric boranes, namely, 4-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([p-(Mes2 B)C6 H4 (NMe3 )]+ , 1, where "Mes" represents mesitylene and "Me" represents methyl) and 2-[bis(2,4,6-trimethylphenyl)boranyl]-N,N,N-trimethylaniline ([o-(Mes2 B)C6 H4 (NMe3 )]+ , 2) has been investigated using density functional theory (DFT) and time dependent-density functional theory (TD-DFT) methods. Natural population analysis indicates that the central boron atoms in 1 and 2 are the most active centers for nucleophilic addition of anions...
May 18, 2017: Journal of Physical Chemistry. A
Henry Lin, Robert Woodrow Leighty, Scott Godfrey, Samantha Boran Wang
Perfusion medium was successfully developed based on our fed-batch platform basal and feed media. A systematic development approach was undertaken by first optimizing the ratios of fed-batch basal and feed media followed by targeted removal of unnecessary and redundant components. With this reduction in components, the medium could then be further concentrated by 2× to increase medium depth. The medium osmolality was also optimized where we found ∼360 mOsm/kg was desirable resulting in a residual culture osmolality of ∼300 mOsm/kg for our cell lines...
July 2017: Biotechnology Progress
Christina Ferousi, Simon Lindhoud, Frauke Baymann, Boran Kartal, Mike Sm Jetten, Joachim Reimann
The most abundant transition metal in biological systems is iron. It is incorporated into protein cofactors and serves either catalytic, redox or regulatory purposes. Anaerobic ammonium oxidizing (anammox) bacteria rely heavily on iron-containing proteins - especially cytochromes - for their energy conservation, which occurs within a unique organelle, the anammoxosome. Both their anaerobic lifestyle and the presence of an additional cellular compartment challenge our understanding of iron processing. Here, we combine existing concepts of iron uptake, utilization and metabolism, and cellular fate with genomic and still limited biochemical and physiological data on anammox bacteria to propose pathways these bacteria may employ...
April 2017: Current Opinion in Chemical Biology
P Veeraraghavan Ramachandran, Ameya S Kulkarni
Ammonia promotes the synthesis of pure ammonia borane (AB) in excellent yields from sodium borohydride and ammonium sulfate in tetrahydrofuran under ambient conditions. An examination of the influence of added ammonia reveals that it is incorporated into the product AB, contrary to its perceived function as a catalyst or a co-solvent. Mechanistic studies point to a nucleophilic attack by ammonia on ammonium borohydride with concurrent dehydrogenation to yield AB.
October 18, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Boran Kartal, Jan T Keltjens
Anaerobic ammonium-oxidizing (anammox) bacteria are one of the latest scientific discoveries in the biogeochemical nitrogen cycle. These microorganisms are able to oxidize ammonium (NH4 + ) with nitrite (NO2 - ) as the oxidant instead of oxygen and form dinitrogen (N2 ) as the end product. Recent research has shed a light on the biochemistry underlying anammox metabolism with two key intermediates, nitric oxide (NO) and hydrazine (N2 H4 ). Substrates and intermediates are converted exploiting the catalytic and electron-transfer potentials of c-type heme proteins known from numerous biochemical reactions and that have acquired new functionality in anammox biochemistry...
December 2016: Trends in Biochemical Sciences
Dongyue Zhang, Senthil K Boopathi, Nikos Hadjichristidis, Yves Gnanou, Xiaoshuang Feng
Polycarbonates were successfully synthesized for the first time through the anionic copolymerization of epoxides with CO2, under metal-free conditions. Using an approach based on the activation of epoxides by Lewis acids and of CO2 by appropriate cations, well-defined alternating copolymers made of CO2 and propylene oxide (PO) or cyclohexene oxide (CHO) were indeed obtained. Triethyl borane was the Lewis acid chosen to activate the epoxides, and onium halides or onium alkoxides involving either ammonium, phosphonium, or phosphazenium cations were selected to initiate the copolymerization...
September 7, 2016: Journal of the American Chemical Society
Naomi M de Almeida, Hans J C T Wessels, Rob M de Graaf, Christina Ferousi, Mike S M Jetten, Jan T Keltjens, Boran Kartal
Electron transport, or oxidative phosphorylation, is one of the hallmarks of life. To this end, prokaryotes evolved a vast variety of protein complexes, only a small part of which have been discovered and studied. These protein complexes allow them to occupy virtually every ecological niche on Earth. Here, we applied the method of proteomics-based complexome profiling to get a better understanding of the electron transport systems of the anaerobic ammonium-oxidizing (anammox) bacteria, the N2-producing key players of the global nitrogen cycle...
October 2016: Biochimica et Biophysica Acta
Wouter J Maalcke, Joachim Reimann, Simon de Vries, Julea N Butt, Andreas Dietl, Nardy Kip, Ulrike Mersdorf, Thomas R M Barends, Mike S M Jetten, Jan T Keltjens, Boran Kartal
Anaerobic ammonium-oxidizing (anammox) bacteria derive their energy for growth from the oxidation of ammonium with nitrite as the electron acceptor. N2, the end product of this metabolism, is produced from the oxidation of the intermediate, hydrazine (N2H4). Previously, we identified N2-producing hydrazine dehydrogenase (KsHDH) from the anammox organism Kuenenia stuttgartiensis as the gene product of kustc0694 and determined some of its catalytic properties. In the genome of K. stuttgartiensis, kustc0694 is one of 10 paralogs related to octaheme hydroxylamine (NH2OH) oxidoreductase (HAO)...
August 12, 2016: Journal of Biological Chemistry
Weidong Chen, Haibo Yu, Guotao Wu, Teng He, Zhao Li, Zaiping Guo, Huakun Liu, Zhenguo Huang, Ping Chen
Ammonium aminodiboranate ([NH4 ][BH3 NH2 BH3 ]) is a long-sought isomer of diammoniate of diborane ([NH3 BH2 NH3 ][BH4 ]) and ammonia borane (NH3 BH3 ) dimer. Our results show that [NH4 ][BH3 NH2 BH3 ] is stable in tetrahydrofuran at -18 °C and decomposes rapidly to NH3 BH2 NH2 BH3 and H2 at elevated temperatures. The decomposition pathway is dictated by the dihydrogen bonding between H(δ+) on NH4 (+) and H(δ-) on BH3 , as confirmed by theoretical calculations. This is in contrast to the interconversion between [NH3 BH2 NH3 ][BH4 ] and (NH3 BH3 )2 , although all three have dihydrogen bonds and the same stoichiometry...
June 1, 2016: Chemistry: a European Journal
Maartje A H J van Kessel, Daan R Speth, Mads Albertsen, Per H Nielsen, Huub J M Op den Camp, Boran Kartal, Mike S M Jetten, Sebastian Lücker
Nitrification is a two-step process where ammonia is first oxidized to nitrite by ammonia-oxidizing bacteria and/or archaea, and subsequently to nitrate by nitrite-oxidizing bacteria. Already described by Winogradsky in 1890, this division of labour between the two functional groups is a generally accepted characteristic of the biogeochemical nitrogen cycle. Complete oxidation of ammonia to nitrate in one organism (complete ammonia oxidation; comammox) is energetically feasible, and it was postulated that this process could occur under conditions selecting for species with lower growth rates but higher growth yields than canonical ammonia-oxidizing microorganisms...
December 24, 2015: Nature
Jianhua Guo, Yongzhen Peng, Lu Fan, Liang Zhang, Bing-Jie Ni, Boran Kartal, Xin Feng, Mike S M Jetten, Zhiguo Yuan
There is great potential to understand the functional diversity of microorganisms that are involved in waste water treatment through metagenomic analyses. This study presents the first metagenomic comparison of taxonomic and functional profiles of the microbial communities occurring in different aggregates from anaerobic ammonium-oxidizing (anammox) bioreactors. The anammox bacterial communities in both biofilm and granule sludge samples showed relatively high abundance and diversity compared with floccular sludge...
September 2016: Environmental Microbiology
Varvara Morozova, Peter Mayer, Guillaume Berionni
Several phosphonium and ammonium triarylborohydrides, which are intermediates in hydrogenation reactions catalyzed by frustrated Lewis pairs, were synthesized in high yield under mild conditions from triaryl boranes, ammonium or phosphonium halides, and triethylsilane. The kinetics and mechanisms of the reactions of these hydridoborate salts with benzhydrylium ions, iminium ions, quinone methides, and Michael acceptors were investigated, and their nucleophilicity was determined and compared with that of other hydride donors...
November 23, 2015: Angewandte Chemie
Andreas Dietl, Christina Ferousi, Wouter J Maalcke, Andreas Menzel, Simon de Vries, Jan T Keltjens, Mike S M Jetten, Boran Kartal, Thomas R M Barends
Anaerobic ammonium oxidation (anammox) has a major role in the Earth's nitrogen cycle and is used in energy-efficient wastewater treatment. This bacterial process combines nitrite and ammonium to form dinitrogen (N2) gas, and has been estimated to synthesize up to 50% of the dinitrogen gas emitted into our atmosphere from the oceans. Strikingly, the anammox process relies on the highly unusual, extremely reactive intermediate hydrazine, a compound also used as a rocket fuel because of its high reducing power...
November 19, 2015: Nature
Francesc Teixidor, Ariadna Pepiol, Clara Viñas
A new class of globular polybranched macromolecules that contain multiple anionic metallacarborane clusters at the o-carborane periphery is reported. The water soluble high boron rich containing molecules could be of interest for boron neutron capture therapy (BNCT) as well as for drug delivery. The reinforced electrostatic noncovalent interactions between anionic polyethylene glycol cobaltabisdicarbollide (PEG-COSAN) branches and the ammonium cation have been shown using ESI-MS.
July 20, 2015: Chemistry: a European Journal
Jiawei Chen, Eugene X-Y Chen
This work reveals the contrasting reactivity of amine/E(C6F5)3 (E = B, Al) Lewis pairs toward linear and cyclic acrylic monomers, methyl methacrylate (MMA) and biorenewable γ-methyl-α-methylene-γ-butyrolactone (γMMBL). While mixing of 2,2,6,6-tetramethylpiperidine (TMP) and B(C6F5)3 leads to a frustrated Lewis pair (FLP), Et3N reacts with B(C6F5)3 to form disproportionation products, ammonium hydridoborate ionic pair and iminium zwitterion. On the other hand, the stoichiometric reaction of either TMP or Et3N with Al(C6F5)3 leads to clean formation of a classic Lewis adduct (CLA)...
2015: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
P Veeraraghavan Ramachandran, Ameya S Kulkarni
An amine-ammonium salt equilibration-metathesis sequence provides high-purity amine-boranes in excellent yields from sodium borohydride in refluxing reagent-grade tetrahydrofuran in an open flask.
June 15, 2015: Inorganic Chemistry
Naomi M de Almeida, Sarah Neumann, Rob J Mesman, Christina Ferousi, Jan T Keltjens, Mike S M Jetten, Boran Kartal, Laura van Niftrik
UNLABELLED: Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite as the terminal electron acceptor to form dinitrogen gas in the absence of oxygen. Anammox bacteria have a compartmentalized cell plan with a central membrane-bound "prokaryotic organelle" called the anammoxosome. The anammoxosome occupies most of the cell volume, has a curved membrane, and contains conspicuous tubule-like structures of unknown identity and function. It was suggested previously that the catalytic reactions of the anammox pathway occur in the anammoxosome, and that proton motive force was established across its membrane...
July 2015: Journal of Bacteriology
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