107-43-7Relevant articles and documents
A New Microbial Pathway for Organophosphonate Degradation Catalyzed by Two Previously Misannotated Non-Heme-Iron Oxygenases
Rajakovich, Lauren J.,Pandelia, Maria-Eirini,Mitchell, Andrew J.,Chang, Wei-Chen,Zhang, Bo,Boal, Amie K.,Krebs, Carsten,Bollinger, J. Martin
, p. 1627 - 1647 (2019)
The assignment of biochemical functions to hypothetical proteins is challenged by functional diversification within many protein structural superfamilies. This diversification, which is particularly common for metalloenzymes, renders functional annotations that are founded solely on sequence and domain similarities unreliable and often erroneous. Definitive biochemical characterization to delineate functional subgroups within these superfamilies will aid in improving bioinformatic approaches for functional annotation. We describe here the structural and functional characterization of two non-heme-iron oxygenases, TmpA and TmpB, which are encoded by a genomically clustered pair of genes found in more than 350 species of bacteria. TmpA and TmpB are functional homologues of a pair of enzymes (PhnY and PhnZ) that degrade 2-aminoethylphosphonate but instead act on its naturally occurring, quaternary ammonium analogue, 2-(trimethylammonio)ethylphosphonate (TMAEP). TmpA, an iron(II)- and 2-(oxo)glutarate-dependent oxygenase misannotated as a γ-butyrobetaine (γbb) hydroxylase, shows no activity toward γbb but efficiently hydroxylates TMAEP. The product, (R)-1-hydroxy-2-(trimethylammonio)ethylphosphonate [(R)-OH-TMAEP], then serves as the substrate for the second enzyme, TmpB. By contrast to its purported phosphohydrolytic activity, TmpB is an HD-domain oxygenase that uses a mixed-valent diiron cofactor to enact oxidative cleavage of the C-P bond of its substrate, yielding glycine betaine and phosphate. The high specificities of TmpA and TmpB for their N-trimethylated substrates suggest that they have evolved specifically to degrade TMAEP, which was not previously known to be subject to microbial catabolism. This study thus adds to the growing list of known pathways through which microbes break down organophosphonates to harvest phosphorus, carbon, and nitrogen in nutrient-limited niches.
In vitro visualization of betaine aldehyde synthesis and oxidation using hyperpolarized magnetic resonance spectroscopy
Allouche-Arnon, Hyla,Gamliel, Ayelet,Sosna, Jacob,Gomori, J. Moshe,Katz-Brull, Rachel
, p. 7076 - 7078 (2013)
Real-time monitoring of betaine aldehyde metabolism at high temporal resolution was accomplished using a hyperpolarized choline analog and 13C-NMR. This represents the first observation of an aldehyde intermediate on hyperpolarized MR and opens the way for kinetic studies of oxidase/dehydrogenase enzymes in vitro and in vivo.
Purification and characterization of an alkaliphilic choline oxidase of fusarium oxysporum
Enokibara, Shogo
, p. 2219 - 2224 (2012)
A novel choline oxidase found in a fungus, Fusarium oxysporum strain V2, was purified to homogeneity as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme has a molecular mass of 128 kDa and consists of two identical subunits. The purified enzyme showed adsorption peaks at 340nm and 450 nm. It showed alkaliphilic pH characteristics: its optimum pH was 9.0-10.0, and it was stable at pH 8.0- 10.2. The Michaelis constant (Km) values for choline and betaine aldehyde were 0.28mM and 0.39mM respectively. Trimethylamino-alcohols, dimethylaminoalcohols, and diethylaminoethanol were substrates for the enzyme, but the Km values for them increased with decreasing numbers of methyl groups on the ammonium headgroup. A marked decrease in the maximum velocity (Vmax) and Vmax/Km values was observed when Nreplaced choline analogs were used as substrate instead of choline. The enzyme had a remarkably higher affinity for choline and betaine aldehyde than do previously reported enzymes. The enzyme oxidized these two substrates more quickly than a choline oxidase from Arthrobacter globiformis, and oxidation by the V2 enzyme was accompanied by an increase in the stoichometric amount of hydrogen peroxide.
Proximate Charge Effects. 5. Enthalpies of Solvent Transfer of Reactants and Transition States in the Saponification of Betaine Ethyl Ester
Haberfield, Paul,Fortier, Daniel
, p. 4554 - 4557 (1983)
The rates and activation enthalpies of the alkaline hydrolysis of betaine ethyl ester were measured in water, in 60 mol percent ethanol-water, and in 60 mol percent dimethyl sulfoxide-water.Unlike the alkaline hydrolysis of ethyl acetate which exhibits a large increase in ΔH on going from water as the solvent to 60 mol percent ethanol-water, no such solvent effect was observed in the present case.Calorimetric determination of the enthalpies of solvent transfer revealed that, whereas there was a large desolvation of the ethyl acetate saponification transition state on transfer into aqueous ethanol, no such desolvation of the betaine ethyl ester transition state took place, an observation which had been made earlier about the saponification of acetylcholine.In 60 mol percent dimethyl sulfoxide-water, a polar, poor hydrogen bond donor solvent, the ΔH for betaine ethyl ester and ethyl acetate saponification were nearly the same as in water as the solvent.Calorimetric determination of the enthalpies of solvent transfer of the saponification transition states of betaine ethyl ester and ethyl acetate from aqueous dimethyl sulfoxide to hydrogen bond donor solvents revealed that the increase in solvation on going to the better solvent was about the same for both esters.
Oxygen- and temperature-dependent kinetic isotope effects in choline oxidase: Correlating reversible hydride transfer with environmentally enhanced tunneling
Fant, Fan,Gadda, Giovanni
, p. 17954 - 17961 (2005)
Choline oxidase catalyzes the flavin-linked oxidation of choline to glycine betaine, with betaine aldehyde as intermediate and oxygen as electron acceptor. Here, the effects of oxygen concentration and temperature on the kinetic isotope effects with deuterated choline have been investigated. The D(kcat/Km) and D/kcat values with 1,2-[2H4]-choline were pH-independent at saturating oxygen concentrations, whereas they decreased at high pH to limiting values that depended on oxygen concentration at ≤0.97 mM oxygen. The k cat/Km and kcat pH profiles had similar patterns reaching plateaus at high pH. Both the limiting kcat/K m at high pH and the pKa values were perturbed to lower values with choline and ≤0.25 mM oxygen. These data suggest that oxygen availability modulates whether the reduced enzyme-betaine aldehyde complex partitions forward to catalysis rather then reverting to the oxidized enzyme-choline alkoxide species. At saturating oxygen concentrations, the D(kcat/Km) was 10.6 ± 0.6 and temperature independent, and the isotope effect on the preexponential factors (AH′/AD′) was 14 ± 3, ruling out a classical over-the-barrier behavior for hydride transfer. Similar enthalpies of activation (ΔH?) with values of 18 ± 2 and 18 ± 5 kJ mol-1 were determined with choline and 1,2-[2H 4]-choline. These data suggest that the hydride transfer reaction in which choline is oxidized by choline oxidase occurs quantum mechanically within a preorganized active site, with the reactive configuration for hydride tunneling being minimally affected by environmental vibrations of the reaction coordinate other than those affecting the distance between the donor and acceptor of the hydride.
Intercharge Distance of Flexible Zwitterionic Molecules in Solution
Chevalier, Yves,Perchec, Pierre Le
, p. 1768 - 1774 (1990)
The conformation of flexible zwitterionic molecules in solutions of polar solvents is studied by means of a NMR chemical shift method.This method makes use of chemical shift changes of NMR lines, induced by the electrostatic field caused by the electrical charges of the zwitterion.The electrostatic field at the observed nucleus is calculated, taking distances of zwitterionic (trimethylammonio)alkanoates in aqueous and methanolic solutions are then deduced from the 13C NMR chemical shift data as a function of the number of methylenes linking the cationic and anionic groups of the zwitterion.The comparison of experimental data with the end to end distances predicted by the rotational isomerism state theory shows that the polymethylene chain has a more folded conformation than the free chain.Electrostatic attraction between the two zwitterionic charges is thus important, although it could be expected that it could be offset by steric hindrance, i.e., by the bulkiness of terminal charged groups.
Micellar Effects upon the Reaction of Betaine Esters with Hydroxide Ion
Al-Lohedan, Hamad,Bunton, Clifford A.,Romsted, Laurence S.
, p. 2123 - 2129 (1981)
The reaction of hydroxide ion with methyl N,N,N-trimethylglycinate (1a) is inhibited by cationic micelles of C14H29NMe3Cl and C16H33NMe3Cl (MTACl and CTACl) besause the substrate is largely in the aqueous pseudophase which is depleted in OH- by the cationic micelles.Added Cl- displaces OH- from the micelles and decreases micellar inhibition.The corresponding reaction of methyl N-dodecyl-N,N-dimethylglycinate (1b) is catalyzed by both MTACl and CTACl which bind both reactants, but this catalysis is reduced by NaCl.Self-micellization of methyl N-hexadecyl-N,N-dimethylglycinate (1c) speeds reaction with OH-, and the rate constants reach plateau values with increasing substrate concentration and are independent of OH-.But addition of either CTACl or NaCl slows reaction because Cl- displaces OH- from the micelle.These diverse rate effents can be accounted for quantitatively in terms of the pseudophase ion-exchange model, which considers reactions in both the aqueous and micellar pseudophases and the distribution of both reactants between the pseudophases.
Free-radical polymerization of itaconic acid in the presence of choline salts: Mechanism of persulfate decomposition
Bednarz, Szczepan,B?aszczyk, Alicja,B?azejewska, Diana,Bogda?, Dariusz
, p. 297 - 304 (2015)
Kinetics of decomposition of persulfate activated by choline in aqueous solution has been studied. Additionally, the products of choline degradation were analyzed by 1H NMR spectroscopy, and betaine aldehyde was identified as the main oxidation product. Thus, radical-chain redox mechanism is postulated to explain experimental results. The mechanism was successfully verified using kinetic modeling approach. Moreover, it was found that due to formation of complex of itaconic acid and choline chloride, the salt solubility of the acid in water was increased. Finally, free-radical polymerization of itaconic acid initiated by persulfate in aqueous solution of the choline salt yielded poly(itaconic acid) with higher molecular weight and increased polydispersity.
Photoluminescent C-dots@RGO probe for sensitive and selective detection of acetylcholine
Wang, Chen-I,Periasamy, Arun Prakash,Chang, Huan-Tsung
, p. 3263 - 3270 (2013)
We have developed a sensitive and selective photoluminescence (PL) quenching assay for the detection of acetylcholine (ACh) that uses reduced graphene oxide decorated with carbon dots (C-dots@RGO). The highly stable C-dots@RGO synthesized from catechin and graphene oxide through a hydrothermal reaction displays excitation-wavelength dependence of PL. Acetylcholinesterase (AChE) converts ACh to choline, which in turn is oxidized by choline oxidase (ChOx) to produce betaine and H2O2 that generates the reactive oxygen species (ROS). The as-produced ROS induces PL quenching of the C-dots@RGO through an etching process. With respect to sensitivity, the optimal reaction/sensing temperature and pH are 37 C and 9.0, respectively, using C-dots@RGO (0.4 mg·mL-1) and AChE and ChOx at the activities of 0.5 and 0.1 unit·mL-1, respectively. The PL intensity (excitation/emission wavelengths 365/440 nm) of the C-dots@RGO is inversely proportional to the concentration of ACh over a range of 0.05-10 nM (r = 0.997), with a limit of detection (signal-to-noise ratio 3) of 30 pM. We have validated this assay by determination of concentrations of ACh in plasma and blood samples, with results of 2.6 ± 0.8 nM (n = 5) and 6.8 ± 0.4 nM (n = 5), respectively. Our study opens an avenue for the detection of various analytes by use of C-dots@RGO in conjunction with different enzymes, substrates, and/or inhibitors.
A label-free silicon quantum dots-based photoluminescence sensor for ultrasensitive detection of pesticides
Yi, Yinhui,Zhu, Gangbing,Liu, Chang,Huang, Yan,Zhang, Youyu,Li, Haitao,Zhao, Jiangna,Yao, Shouzhuo
, p. 11464 - 11470 (2013)
Sensitive, rapid, and simple detection methods for the screening of extensively used organophosphorus pesticides and highly toxic nerve agents are in urgent demand. A novel label-free silicon quantum dots (SiQDs)-based sensor was designed for ultrasensitive detection of pesticides. This sensing strategy involves the reaction of acetylcholine chloride (ACh) with acetylcholinesterase (AChE) to form choline that is in turn catalytically oxidized by choline oxidase (ChOx) to produce betaine and H2O2 which can quench the photoluminescence (PL) of SiQDs. Upon the addition of pesticides, the activity of AChE is inhibited, leading to the decrease of the generated H 2O2, and hence the PL of SiQDs increases. By measuring the increase in SiQDs PL, the inhibition efficiency of pesticide to AChE activity was evaluated. It was found that the inhibition efficiency was linearly dependent on the logarithm of the pesticides concentration. Consequently, pesticides, such as carbaryl, parathion, diazinon, and phorate, were determined with the SiQDs PL sensing method. The lowest detectable concentrations for carbaryl, parathion, diazinon, and phorate reached 7.25 × 10-9, 3.25 × 10-8, 6.76 × 10-8, and 1.9 × 10-7 g/L, respectively, which were much lower than those previously reported. The detecting results of pesticide residues in food samples via this method agree well with those from high-performance liquid chromatography. The simple strategy reported here should be suitable for on-site pesticides detection, especially in combination with other portable platforms.
