Jasmonates, a collective term combining both jasmonic acid (JA) and related derivatives, are ubiquitously distributed in the plant kingdom. They are characterized as lipid-derived signal molecules which mediate a plethora of physiological functions, in particular stress responses, male fertility, and a multitude of developmental processes. In the course of JA ...

d-Amino acid oxidase (DAAO) was used to study the oxidative deamination of racemic mixtures of d,l-methionine in its soluble and immobilized forms and thus obtain the corresponding alpha-keto acid. The soluble enzyme form was obtained from a Trigonopsis variabilis CBS 4095 extract, free of l-amino acid oxidase, and was co-immobilized ...

Preparation, structural characterization, and reactivity of 3-[bis(trifluoroacetoxy)iodo]benzoic acid and 3-[hydroxy(tosyloxy)iodo]benzoic acid, new recyclable iodine(III) reagents derived from 3-iodosylbenzoic acid, are described. The reduced form of these reagents, 3-iodobenzoic acid, can be easily recovered from the reaction mixtures using ion-exchange resin or basic aqueous workup followed by acidification with HCl.

The stability and the reactivity of mono- and diprotonated 4-heterocyclohexanones as well as cyclohexanone in triflic acid have been studied at the PBE0/aug-cc-pvtz//PBE0/6-31+G** level of theory. In all cases the first protonation is an exergonic process occurring at a carbonyl oxygen except for 4-piperidone where a nitrogen atom is protonated ...

D-Methionine was converted to L-methionine in a reaction system where four enzymes were used. D-amino acid oxidase (D-AAO) from Arthrobacter protophormiae was used for the complete conversion of D-methionine to 2-oxo-4-methylthiobutyric acid. Catalase was added to prevent 2-oxo-4-methylthiobutyric acid decarboxylation. In the second reaction step, L-phenylalanine dehydrogenase (L-PheDH) from Rhodococcus ...

Hypohalous acids are generated from the oxidation of halide ions by myeloperoxidase and eosinophil peroxidase in the presence of H2O2. These oxidants are potent antibacterial agents, but excessive production can result in host tissue damage, with this implicated in a number of human pathologies. Rate constants for HOCl with lipid ...

New opportunities for the conversion of glycerol into value-added chemicals have emerged in recent years as a result of glycerol's unique structure, properties, bioavailability, and renewability. Glycerol is currently produced in large amounts during the transesterification of fatty acids into biodiesel and as such represents a useful by-product. This paper ...

Quinol esters 2b, 2c, and 3b and sulfonamide 4c were investigated as possible precursors to 4-alkylaryloxenium ions, reactive intermediates that have not been previously detected. These compounds exhibit a variety of interesting reactions, but with one possible exception, they do not generate oxenium ions. The 4-isopropyl ester 2b predominantly undergoes ...

The potential of the Aspergillus niger type A feruloyl esterase (AnFaeA) for the synthesis of various phenolic acid esters was examined using a ternary-organic reaction system consisting of a mixture of n-hexane, 1- or 2-butanol and water. Reaction parameters including the type of methyl hydroxycinnamate, the composition of the reaction ...

The direct kinetic formation of spiroketals from mixed ketal-alcohol precursors under acid catalysis was studied using four differently substituted systems. In all cases, the exclusive formation of the anomeric isomer was observed under equilibrating conditions. However, the formation of the nonanomeric spiroketal isomer was observed if the reaction was performed ...

Reaction of cyclic thioanhydrides with amines affords amides functionalized with thioacids, which can be trapped in situ with electron-deficient azides or, preferably, 2,4-dinitrobenzenesulfonamides. In this manner the cyclic thioanhydride serves as a linchpin in a three-component coupling sequence. The use of thiomaleic anhydride and a bifunctional nucleophile extends the process ...

BACKGROUND AND AIMS: When green coffee is stored for a prolonged time the coffee quality decreases distinctively. Apart from well-known 'off-notes' that arise from undesired oxidations of lipids, a typical 'flattening' of the cup quality is detectable. In order to elucidate the biological causes for this phenomenon, differentially processed coffees ...

The kinetics of reactions of acceptor-stabilized carbanions 2a-m with benzylidenebarbituric and -thiobarbituric acids 1a-e has been determined in a dimethyl sulfoxide solution at 20 degrees C. Second-order rate constants were employed to determine the electrophilicity parameters E of the benzylidenebarbituric and -thiobarbituric acids 1a-e according to the correlation equation log ...

Utility of a water-soluble deep cavity cavitand, octa acid, as a reaction medium is illustrated by carrying out photochemical reactions of a stilbene and a styrene included within the octa acid in water. Geometric isomerization of trans-4,4'-dimethyl stilbene is restricted while dimerization of 4-methyl styrene is facilitated within the octa ...

Cysteine sulfenic acid has been generated in alkaline aqueous solution by oxidation of cysteine with hypohalous acid (HOX, X = Cl or Br). The kinetics and mechanisms of the oxidation reaction and the subsequent reactions of cysteine sulfenic acid have been studied by stopped-flow spectrophotometry between pH 10 and 14. ...

The kinetics of formation of amide, 4, from the corresponding carboxylic acid by reaction with the isopropyl ester of methionine (MIPE), mediated by carbodiimide EDCI, 1, and HOBt, 2, have been studied in 1-methyl-2-pyrrolidinone (NMP) using reaction calorimetry. The reaction rates have been found to be independent of the concentration ...

We propose a new similarity measure operating in the space spanned by the potential values, evaluated at atoms constituting the benzene ring and the COOH group in para-substituted benzoic acids and at benzene ring atoms in monosubstituted benzenes. The similarity measures are equivalent to the Euclidean distance between points in ...

We apply accurate quantum chemistry methods to study the thermochemistry of molecular clusters containing ammonia, water, and sulfuric acid and investigate initial reaction steps in atmospheric nucleation by calculating free energies for the related reactions. The results indicate that ammonia is a key reactant enhancing the growth of small water-sulfuric ...

A recently proposed model of non-autocatalytic reactions in dipeptide formation that leads to spontaneous symmetry breaking and homochirality was examined. The model is governed by activation, polymerization, epimerization, and depolymerization of amino acids. Symmetry breaking was determined to result primarily from the different rates of reactions that involve homodimers and ...

Hydrolysis of biomass waste (such as fish waste, chicken waste, hair and feather) to produce amino acids was studied in sub-critical water, with reaction temperatures from 180 to 320 degrees C and reaction pressures from 3 to 30 MPa. The product of amino acid was determined by Amino Acid Analyzer ...

This paper presents experimental results on the catalytic effect of volcanic sand on benzothiazole ozonation. Experiments were assessed at laboratory scale, in a differential circular flow reactor composed of a volcanic sand fixed bed column of 19 cm3 and a 1 dm3 storage tank, operated in batch mode at 20 ...

This study was directed to look at the chemical composition of maleo-pimaric and fumaro-pimaric rosins made of unmodified rosin with maleic anhydride (MA) or fumaric acid (FA). The results showed that one peak of a maleopimaric acid (MPA) adduct on the chromatogram was obtained when a sample of this reaction ...

Oscillations in the platinum redox potential during the reaction of bromate ions with acetonedicarboxylic acid catalyzed by Mn(II) ions were observed. The volume of gaseous carbon dioxide produced was measured. A nonoscillatory course was found both at the slow and rapid stirring rates for carbon dioxide evolution. The perturbation experiments ...

Yellow 9-methyldipyrrinones can be converted readily and in high yields to symmetric linear tetrapyrroles, blue biliverdinoids, which are cleaved in half, smoothly at room temperature to afford yellow 9-H dipyrrinones, and 9-CHO dipyrrinones as their violet to orange colored adducts with the carbon acid used for the scission: thiobarbituric acid ...

This study examines the influence of ammonia (NH3) on secondary organic aerosol (SOA) formation from the alpha-pinene/ozone oxidation system for dry and humid conditions. Aerosol yield differed depending on which OH scavenger was used, with the highest yield noted for CO, followed by cyclohexane and 2-butanol. Number and volume concentrations ...

The B3LYP/6-311+G(d,p) description is employed to study the heterolytic ring opening mechanisms under microsolvation conditions for ethylene oxide in acidic, neutral, and alkaline environments. In acid and alkaline media, a concerted trans S(N)2 reaction is strongly favored as compared to the corresponding cis reaction. The importance of the nucleophile, water ...

Fatty acid nitration by nitric oxide-derived species yields electrophilic products that adduct protein thiols, inducing changes in protein function and distribution. Nitro-fatty acid adducts of protein and reduced glutathione (GSH) are detected in healthy human blood. Kinetic and mass spectrometric analyses reveal that nitroalkene derivatives of oleic acid (OA-NO2) and ...

Treatment of 5-nitroisocoumarin with aromatic acyl chlorides under Friedel-Crafts conditions gives 3-aryl-5-nitroisocoumarins, rather than the expected 4-acyl-5-nitroisocoumarins. This procedure was optimized for reaction temperature (150 degrees C), solvent (nitrobenzene), and Lewis acid (SnCl4). Reaction of 5-nitroisocoumarin with [13C]-carbonyl benzoyl chloride under the optimum conditions gave 5-nitro-3-phenylisocoumarin in which the 13C ...

Quinoline (1) and isoquinoline (2), upon activation by strong acids, lead to intermediate N,C-diprotonated dications, which are involved in reactions with weak nucleophiles. Thus, 1 and 2 undergo selective ionic hydrogenation with cyclohexane in CF3SO3H-SbF5, HBr-AlBr3-CH2Br2, or HCl-AlCl3-CH2Cl2 acid systems to give their 5,6,7,8-tetrahydro derivatives. They also readily condense with ...

A biosynthetic intermediate of violacein produced by the mixed enzymes of VioABDE was elucidated to be 5-(5-hydroxy-1H-indol-3-yl)-3-(1H-indol-3-yl)-1H-pyrrole-2-carboxylic acid, named protoviolaceinic acid, indicating that VioC, responsible for the final biosynthetic step, works to oxygenate at the 2-position of the right side indole ring, and that the oxygenation reaction to form the ...

The complete curing of furfuryl alcohol (FA), was studied by chemorheological analysis and model-free kinetics under isothermal and non-isothermal modes. Polymerization of FA under acidic catalysis involves complex reactions, with several steps (such as condensations and Diels-Alder cycloadditions). To account for the polymerization complexity, kinetic analysis of DSC data was ...

Reactive desorption electrospray ionization (reactive DESI) is demonstrated to be a rapid and sensitive method for the direct detection of alkyl methylphosphonic acids, the hydrolysis products and metabolites of the chemical warfare (CW) agents VX (S-2-diisopropylaminoethyl-O-ethyl methylphosphonothiolate) and GB (sarin, isopropylmethyl phosphonofluoridate). Rapid and sensitive detection of these compounds is ...

Bioleaching of metals from hazardous spent hydro-processing catalysts was attempted in the second stage after growing the bacteria with sulfur in the first stage. The first stage involved transformation of elemental sulfur particles to sulfuric acid through an oxidation process by acidophilic bacteria. In the second stage, the acidic medium ...

Nodulation is the quantitatively predominant insect cellular immune function activated in response to bacterial, fungal and some viral infections. We posed the hypothesis that parasitoid insects express melanotic nodulation reactions to viral challenge and that eicosanoids mediate these reactions. Treating fifth-instar larvae of the ichneumonid endoparasitoid Pimpla turionellae with Bovine ...

Feruloylated mono- and di-acylglycerols were synthesized in a two step reaction: ethyl ferulate was first transesterified with glycerol and then this was esterified with oleic acid. The yield of the combined feruloylated mono- and di-acylglycerols in the second reaction reached 96% when esterification of 0.3 g transesterification products with 2.22 ...

A comparison between a tetramolecular mechanism (J. Org. Chem. 2007, 72, 3031) and our previously proposed mechanism has been performed. The results show that the tetramolecular mechanism is less favored in terms of Gibbs free energy, and therefore, the reaction in acidic media is acid catalyzed. The role of the ...

For the determination of substrate specificities of thermophilic alpha-aminotransferases (AATs), a novel high-throughput assay method was developed. In this method, a thermophilic omega-aminotransferase (OAT) and a thermophilic aldehyde dehydrogenase (ALDH) are coupled to the AAT reaction. Glutamic acid is used as an amino group donor for the AAT reaction yielding ...

Stereoselectivity of TiCl4-mediated aldol reactions from (S)-2-benzyloxy-3-pentanone is dramatically improved when the reaction is carried out in the presence of 1.1 equiv of tetrahydrofuran (THF) or 1,2-dimethoxyethane (DME). The resultant 2,4-syn-4,5-syn adducts are then obtained in diastereomeric ratios up to 97:3, which proves that the appropriate choice of the Lewis ...

The mechanism for the atmospheric oxidation of methanesulfinic acid (MSIA) has been studied. This is the first theoretical study of the reaction between MSIA and the OH radical. All the possible channels in this reaction have been studied theoretically, and their corresponding rate constants have been evaluated under the variational ...

Phototransformation of the herbicide fluometuron (1 microM) in natural sunlight was investigated in neutral Milli-Q water and in synthetic waters containing either fulvic acids, nitrate ions or both in order to mimic reactions taking place in aquatic environments. Fluometuron degradation followed a pseudo-first order kinetics. The reaction was faster in ...

Hydroxycarboxylic acid monomers can be used to prepare industrially important polymers. Enzymatic production of such hydroxycarboxylic acids is often preferred to chemical production since the reactions are run at ambient temperature, do not require strongly acidic or basic reaction conditions, and produce the desired product with high selectivity at high ...

We examined the synthesis of benzoyl glucoside using the transglucosylation reaction of sucrose phosphorylase. Sucrose phosphorylase from Streptococcus mutans showed marked transglucosylating activity, particularly under acidic conditions. On the other hand, sucrose phosphorylase from Leuconostoc mesenteroides showed very weak transglucosylating activity. Three main products were detected from the reaction mixture ...

The ethanolic extract of the root of Tephrosia purpurea was screened for in vitro antioxidant properties using standard procedures. The ethanolic extract exhibited IC(50) values of 132.31±8.79 and 405.22±15.09 respectively in DPPH and nitric acid radical inhibition assay. These values were slightly more than those obtained for ascorbic acid and ...

Progress in the understanding of interfacial molecular recognition kinetics is obtained by use of the sweeping technique for experimental studies of the reaction kinetics between a host monolayer and a non-surface-active species dissolved in the aqueous subphase. The experimental results show that the interfacial recognition reaction between a 2C(11)H(23)-melamine (2,4-di(n-undecylamino)-6-amino-1,3,5-triazine) ...

Ayers, Parr, and Pearson recently showed that insight into the hard/soft acid/base (HSAB) principle could be obtained by analyzing the energy of reactions in hard/soft exchange reactions, i.e., reactions in which a soft acid replaces a hard acid or a soft base replaces a hard base [J. Chem. Phys., 2006, ...

The effect of steric and electronic environments around the sulfur and nitrogen atoms and the role of nonbonded S...O/N interactions on the cyclization reactions of amide substituted benzene sulfenic acids are described. The reaction profiles and the role of different substituents on the cyclization are investigated in detail by theoretical ...

Diacylglycerol (DAG) and triacylglycerol (TAG) as responses on optimization of DAG production using a dual response approach of response surface methodology were investigated. This approach takes the molecular equilibrium of DAG into account and allows for the optimization of reaction conditions to achieve maximum DAG and minimum TAG yields. The ...

An environmentally benign and volume efficient process for enzymatic production of alkanolamides is described. Immobilized Candida antarctica lipase B, Novozym435, was used to catalyze the condensation of lauric acid with monoethanolamine. The reaction temperature of 90 degrees C was required to keep the reactants in a liquid state. Stepwise addition ...

Hydrophobically modified chitosan microparticles were produced by various syntheses carried out as heterogeneous phase reactions. Perfluorinated carbonyl components such as carbonic acids and acid chlorides were used as hydrophobization agents. To enhance the layer stability preceding cross-linkages between the chitosan macromolecules were introduced. These cross-linkages involve some of the chitosan ...

A homologous series of cationic gas-phase clusters of dicarboxylic acids (oxalic acid, malonic acid, succinic acid, glutaric acid, and adipic acid) generated via electrospray ionization (ESI) are investigated using collision-induced dissociation (CID). Singly charged cationic clusters with the composition (Na(+))(2n+1)(dicarboxylate(2-))(n), where n = 1-5, are observed as major gas-phase species. ...