2-chloropropionate Research Articles

Structure-activity relationship of 17 structural analogues of n-butyric acid upon c-myc expression.

Terminal differentiation of hematopoietic cells in vivo and in vitro is almost invariably accompanied by down-regulated expression of the c-myc proto-oncogene. Constitutive expression of c-myc in tumor cells inhibits terminal differentiation and maintains proliferation. In Burkitt's lymphoma, chromosomal translocations cause a deregulation of the c-myc gene through fusion of this locus with one of the immunoglobulin gene loci. However, the down-regulation of c-myc by n-butyric acid, a potent inducer of differentiation, is also observed in BL cells. Unlike other inducers of differentiation such as dimethylsulfoxide or hexamethylenebisacetamide, which down-regulate c-myc expression, albeit transiently, n-butyric acid causes a continuous, transcriptional shut-off. Because of the possible therapeutic implication of this finding, we have assayed structural analogues of n-butyric acid for their effect on c-myc expression in Burkitt's lymphoma cells. Of the analogues tested, 12 were active and 5 were inactive. Only unbranched fatty acids with 4 and 5 carbon atoms showed activity, a 4-carbon chain being optimal. 3-chloropropionic acid had maximal activity at a 3-fold lower concentration than n-butyric acid (1 mM versus 3 mM). The corresponding ester-analogues were equally effective. Those analogues found capable of down-regulating c-myc in Burkitt's lymphoma cells were similarly effective in their ability to induce terminal differentiation in murine erythroleukemia cells.

Glutathione depletion in the liver and brain produced by 2-chloropropionic acid: relevance to cerebellar granule cell necrosis.

L- and D-2-chloropropionic acid (L-CPA and D-CPA) produce selective damage to granule cells of the rat cerebellum by a mechanism that is not currently understood. We have demonstrated that both L- and D-CPA produce a rapid, dose and time dependent depletion of liver non-protein sulphydryl (NP-SH) content, mainly glutathione (GSH), while in the cerebellum and forebrain, there is a slower, dose and time dependent decrease in NP-SH. Twenty-four hours after a single dose of 750 mg/kg L-CPA (a dose sufficient to produce cerebellar toxicity, but a time prior to the onset of cellular necrosis), the content of total GSH was depleted by 85% in the cerebellum and to a lesser degree in the forebrain, while no increase in oxidised glutathione was observed in either tissue. In vitro both L- and D-CPA caused a marked reduction in GSH concentration when incubated with hepatic cytosol but not hepatic microsomes or brain cytosol. The hepatic cytosolic depletion appeared to be due to a direct reaction catalysed by a theta class glutathione S-transferase. A GSH adduct of L-CPA was isolated by high pressure liquid chromatography and identified by mass spectrometry as 2-S-glutathionyl propanoic acid, confirming a direct substitution reaction. No GSH adducts were formed by cerebellar or forebrain cytosol, suggesting that the particular isoform of glutathione S-transferase catalysing the reaction may not be present in the brain. We suggest that the marked and sustained CPA-mediated GSH depletion in the granule cells of the cerebellum may render these cells more vulnerable to oxidative free radical damage.

Cloning, sequencing and expression in Escherichia coli of two Rhizobium sp. genes encoding haloalkanoate dehalogenases of opposite stereospecificity.

A 6.5-kp EcoRI fragment of genomic DNA from a Rhizobium sp. cloned into pUC19 was able to endow Escherichia coli K-12 with the novel ability to grow at the expense of 2-chloropropionic acid. Subcloning showed that this property was a consequence of two dehalogenases encoded on a 2.2-kb PstI fragment. Further subcloning of the PstI fragment led to two constructs that encoded, separately, dehalogenase activity that acted stereospecifically on D-2-chloropropionic acid and L-2-cloropropionic acid, respectively. The genes encoding these two stereospecific dehalogenases have been sequenced and shown to be separated by 177 bp of non-coding DNA. Expression of the dehalogenase genes involved the vector promoter, suggesting that the anticipated Rhizobium sp. regulatory sequences were not functional in E. coli. Comparison of the deduced amino acid sequences of the two dehalogenases (18% identity) indicated with any other 2-chloropropionic acid dehalogenase studied so far.

Effect of solid salt hydrates on the asymmetric esterification of 2-chloropropionic acid :Control of water activity in organic solvent

Effect of solid salt hydrates on the asymmetric esterification of 2-chloropropionic acid :Control of water activity in organic solvent

Synthesis of a New Chitin Derivative, (1-Carboxyethyl)chitosan

Abstract A new chitin derivative, (1-carboxyethyl)chitosan, was synthesized from chitin and chitosan by the reaction with 2-chloropropionic acid, and its activation effect on canine polymorphonuclear cells (PMNs) was evaluated. The degree of substitution was increased by the repetition of the reaction, but the simultaneous N-deacetylation proceeded. N-Selective 1-carboxyethylation of chitosan was achieved by reductive N-alkylation with 2-oxopropionic acid and NaBH4.

Selective Synthesis of .alpha.-Chloropropanoic Acid

Propanoic acid was selectively chlorinated to 2-chloropropanoic acid in a laboratory scale semibatch reactor operating at atmospheric pressure and in a temperature range of 70-110°C. Chlorosulfonic acid was used as a catalytic agent and molecular oxygen as a radical scavenger. 2,2- and 2,3-dichloropropanoic acids were formed as byproducts. The chlorination kinetics was autocatalytic, when the catalyst concentration was maintained constant by addition. When all of the catalyst was introduced in the beginning of the experiment, a decreasing chlorination rate was observed because of decomposition of the catalyst. The primary reaction product from catalyst decomposition was sulfopropanoic acid, which under the reaction conditions is probably decomposed to gaseous products. The explanation of the autocatalysis is the increase of the acidity of the liquid phase during the progress of the reaction. The autocatalytic kinetics was explained with a reaction mechanism involving the acid-catalyzed enolization of the key intermediate, propanoyl chloride, as a rate-determining step. In the absence of air a radical mechanism contributed to the overall kinetics, which resulted in polychlorinated products. Rate equations based on the autocatalytic ionic mechanism and radical chlorination mechanism were derived, and the kinetic parameters included in the equations were estimated with nonlinear regression analysis from the semibatch reactor data

New Evidence for Dimerization-Dependence of the Activity ofCandida RugosaLipase

The specific activity of the lipase of Cundidu rugosu decreases with increasing enzyme concentration even in the presence of soluble substrates. Data about the hydrolysis of 2-chloropropionic acid ethyl ester (CPEE) had suggested that this phenomenon may be caused either by dimerization of the lipase or by adsorption onto the reactor wall. In order to distinguish between both models, experiments were carried out by changing not only the enzyme concentration but also the wetted surface area of the reaction vessel. These novel data reveal that wetted glass surfaces are of only minor importance - if any. Thus, the decrease of activity seems to be caused by some kind of dimerization of the lipase. In addition, it is shown that adsorption onto hydrophobic surfaces can have a dramatic effect on the specific activity. In the presence of large hydrophobic surface areas the specific activity is found to be almost as high as that observed in the presence of insoluble substrate. The analysis of a commonly used test ...

Matrix effects in plasma desorption mass spectrometry

In Plasma Desorption (PD) Mass Spectrometry, valine/matrix mixtures have been studied in order to specify the influence of a matrix during the desorption-ionization (DI) of volume. The different matrices used were carboxylic acids (barbituric acid, 2-chloronicotinic acid, 3-chloropropionic acid, cysteine, pentafluorobenzoic acid, picric acid, sinapinic acid) and CsI, an inorganic salt. Three effects are proposed to explain the influence of each matrix on the DI of valine: a physical effect, a chemical effect and a (de)cationization effect. Thermodynamic diagrams are proposed to explain each effect. Each matrix gives either a specific effect or a superimposition of effects. The concentration effect of matrices is also studied.

Degradation of 2-chloroallylalcohol by a Pseudomonas sp

Three Pseudomonas strains capable of utilizing 2-chloroallylalcohol (2-chloropropenol) as the sole carbon source for growth were isolated from soil. The fastest growth was observed with strain JD2, with a generation time of 3.6 h. Degradation of 2-chloroallylalcohol was accompanied by complete dehalogenation. Chloroallylalcohols that did not support growth were dechlorinated by resting cells; the dechlorination level was highest if an alpha-chlorine substituent was present. Crude extracts of strain JD2 contained inducible alcohol dehydrogenase activity that oxidized mono- and dichloroallylalcohols but not trichloroallylalcohol. The enzyme used phenazine methosulfate as an artificial electron acceptor. Further oxidation yielded 2-chloroacrylic acid. The organism also produced hydrolytic dehalogenases converting 2-chloroacetic acid and 2-chloropropionic acid.

Relevance of enantiomeric separations in environmental science

A significant number of all organic chemicals that are released into the environment are racemic mixtures. Most environmental regulations and scientific environmental studies treat racemic mixtures as though they were single, pure compounds. This can lead to incorrect toxicological, distribution, degradation and other data. A series of new enantioselective chromatographic techniques have been developed that allow the facile separation and quantitation of chiral compounds of environmental importance. Nineteen racemic compounds that have been or currently are being released to the environment are resolved. These include: rodenticides—Warfarin, Coumachlor and Coumafuryl; insecticides—Crufomate, Bulan, Fonofos, Mitotane; insect repellent—Ethohexadiol; herbicides and fungicides—Ancymidol, Silvex, Napropamide, phenyl mercuric lactate, 2-[3-chlorophenoxy]propionamide, and 2-chloropropionic acid; and halocarbons—1,2-dichloropropane, 2-bromo-1-chloropropane, 1,2-dibromo-3-chloropropane, 2,3-dichlorobutane and α-1,2,3,4,5,6-hexachlorocyclohexane. Several examples are given to illustrate the importance of enantioselective measurements of these and other compounds. Choosing the proper chromatographic technique and chiral stationary phase based on analyte structure is also discussed.

Studies of the role of water on some imine–acid complexes by means of Raman spectroscopy

The percentages of protonation were determined for a conjugated Schiff base trans, trans-2,4-heptadienylidene tert-butylamine in the presence of 3-chloropropionic acid (CPR) and dichloroacetic acid (DCA) in three solvents of different polarities. In dioxane, a solvent of low polarity, protonation is only important for the strong acid DCA (50–60%). By using solvents of higher polarities, protonation is seen to increase and is almost complete for DCA in ethanol. When water molecules are added to these systems, hydrolysis of the Schiff base, measured inside the time span of the experiments (10 min), occurs readily in dioxane, is very slow in a chloroform–dioxane mixture (9:1), and is totally absent in a mixture of ethanol–dioxane (1:9). Results indicate that water does not mediate protonation in all three sets of solvent combinations. The results are also discussed in terms of the possible role that water molecules could have in the visual and bacterial pigments.

Spectral and kinetic characteristics of the α-propionic acid methyl ester radical in cyclohexane and water

The α-propionic acid methyl ester radical was produced in dissociative electron capture reaction of 2-chloropropionic acid methyl ester. The absorption maxima of the radical are at 310 and 300 nm in cyclohexane and water with extinction coefficients of 440±50 and 400±50 mol−1 dm3 cm−1. The second order decay rate parameter in water is (2.3±0.5)×109 mol−1 dm3 s−1. The peroxy radicals have the characteristics: λmax=265–270 nm, emax=700–900 mol−1 dm3 and 2k=(7±2)·108 mol−1 dm3 s−1.

Alcohol Induced Reversal of Enantioselectivity in a Lipase Catalyzed Resolution of 2-Chloropropionic Acid

Alcohol induced reversal of enantioselectivity in the esterification of 2-chloropropionic acid using lipase from Candida cylindracea has been investigated. It was found that an alcohol having substituents both at the α- and the β-carbon preferentially esterified the S-acid, while a straight chain alcohol preferentially esterified the R-acid. Intermediate enantioselectivities were obtained with alcohols having substituents either at the α- or the β-carbon, but still in favor of the R-acid. An acyl binding domain composed of three subsites is proposed for this lipase; one for the hydrocarbon chain, a second for a methyl substituent and a third for an electronegative substituent.

Characterization of the haloacid dehalogenase from Xanthobacter autotrophicus GJ10 and sequencing of the dhlB gene

The haloacid dehalogenase of the 1,2-dichloroethane-utilizing bacterium Xanthobacter autotrophicus GJ10 was purified from a mutant with an eightfold increase in expression of the enzyme. The mutant was obtained by selecting for enhanced resistance to monobromoacetate. The enzyme was purified through (NH4)2SO4 fractionation, DEAE-cellulose chromatography, and hydroxylapatite chromatography. The molecular mass of the protein was 28 kDa as determined with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 36 kDa as determined with gel filtration on Superose 12 fast protein liquid chromatography. The enzyme was active with 2-halogenated carboxylic acids and converted only the L-isomer of 2-chloropropionic acid with inversion of configuration to produce D-lactate. The activity of the enzyme was not readily influenced by thiol reagents. The gene encoding the haloacid dehalogenase (dhlB) was cloned and could be allocated to a 6.5-kb EcoRI-BglII fragment. Part of this fragment was sequenced, and the dhlB open reading frame was identified by comparison with the N-terminal amino acid sequence of the protein. The gene was found to encode a protein of 27,433 Da that showed considerable homology (60.5 and 61.0% similarity) with the two other haloacid dehalogenases sequenced to date but not with the haloalkane dehalogenase from X. autotrophicus GJ10.

Catalytic action of L‐2‐halo acid dehalogenase on long‐chain L‐2‐haloalkanoic acids in organic solvents

A Lyophilized preparation of L-2-halo acid dehalogenase was not only stable but also catalytically active in anhydrous dimethyl sulfoxide, toluene, and other organic solvents. 2-Halo acids with long alkyl (C(5)-C(16)) or aromatic (phenyl and benzyl) side chains were inert in water but dehalogenated effectively in anhydrous dimethyl sulfoxide by the lyophilized enzyme. Long chain 2-haloalkanoic acids such as 2-bromohexadecanoic acids were better as substrate than short-chain halo acids (e.g., 2-chloropropanoic acid). The dehalogenation proceed with inversion of C(2) configuration to produce the corresponding (2R)-2-hydroxy acids in anhydrous dimethyl sulfoxide in the same way as found in water.

Retinylidene Schiff bases in phosphatidylcholine reverse micelles: formation, protonation and stability

All-trans-N-retinylidene-n-butylamine 3 has been formed in inverted micelles of phosphatidylcholine (PC)–hexane containing varying amounts of water ([H2O]/[PC]= 0–3) and the formation, protonation and stability have been studied. The micelles have been found to catalyse the Schiff-base formation. The Schiff-base was found to be stable in the presence of structured water molecules bonded to the polar head groups of the micelles. A larger water-pool causes the decomposition of the Schiff-base. Schiff-base 3 intercalated in the inverted micelle was found to undergo protonation in the presence of 3-chloropropionic acid, the extent of which depended on the water-pool size. The results are discussed in terms of the formation, protonation and stability of retinylidene Schiff-base chromophores in rhodopsins.

Total conversion of racemic 2-chloropropionic acid into d-lactate by combination of enzymatic and chemical dehalogenations

We have developed a simple method for the total conversion of racemic 2-chloropropionic acid into d-lactic acid with an enantiomeric excess (e.e.) of about 94%. l-2-Chloropropionic acid is fully converted to d-lactic acid with l-2-halo acid dehalogenase, and the unreacted d-2-chloropropionic acid is dehalogenated chemically, retaining its configuration to produce d-lactic acid.

The dyeing behaviour of cotton modified with chloropropionyl chloride and related compounds

Cotton fabric was esterified with chloropropionyl chloride followed by reaction with amines, in order to introduce primary, secondary, tertiary and quaternary amino residues. The reactive dyeing proper ties of these chemically modified fibres were studied, especially from the point of view of dyeing in the pH region 5-7 without added electrolyte. The conditions employed to introduce amino residues on the chloropropionated cotton appeared to affect the ultimate mode of attachment of the amino group. These reactions have been studied and a reaction scheme proposed involving the chloropropionic acid acting as a leaving group under severe animation conditions.

Retinylidene schiff bases in alkylammonium carboxylate reversed micelles

All- trans-retinal, incorporated into dodecylammonium propionate, dodecylammonium 3-chloropropionate and dodecylammonium trifluoroacetate reversed micelles in cyclohexane containing different amounts of solubilized water, gave all- trans- N-retinylidene- n-dodecylamine. Formation of all- trans- N-retinylidene- n-dodecylamine was complete within a few minutes when all- trans-retinal was solubilized along with l-lysine in reversed-micellar dodecylammonium propionate in cyclohexane as compared to the several hours required for the comparable reaction to occur in the absence of lysine. In situ formed all- trans- N-retinylidene- n-dodecylamine was not protonated by the acidic moiety (i.e., propionate, 3-chloropropionate or trifluoroacetate anions) of dodecylammonium propionate, dodecylammonium 3-chloropropionate or dodecylammonium trifluoroacetate reversed micelles. Addition of propionic or 3-chloropropionic acid did not cause observable protonation of the reversed-micelle-incorporated all- trans- N-retinylidene- n-dedecylamine. Addition of strong trifluoroacetic acid to reversed micellar solutions of all- trans- N-retinylidene- n-dodecylamine caused protonation as well as hydrolysis to retinal. Retinylidene Schiff bases are protected from protonation by strongly held surfactant-ion pairs which may model proton channels whose function is controlled by protein conformational changes.

Retinylidene Schiff bases in surfactant-solubilized water pools in heptane

All-trans-retinal (1) was reacted with n-butylamine in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles in heptane to form all-trans-N-retinylidene–n-butylamine Schiff bases (2). The extent of protonation of 2 by 3-chloropropionic acid (CPA) to give 3 in AOT reverse micelles in heptane was found to depend on the ratio of [CPA] to [2], as well as on [H2O]/[AOT] (i.e., on the ω value). At any given [2] and ω values, increasing amounts of CPA increased the protonation and at any given constant [2] and [CPA], increasing ω values also increased the protonation. Over a period of 24 hours, there was only 4% decomposition of 2 in AOT reverse micelles in heptane at ω = 24. Conversely, in three hours, 23% of 3 decomposed in the same system. The trans to cis photoisomerization of 2 in heptane occurred at a much faster rate in the presence of AOT reverse micelles than in their absence. The appearance of carboxylate peaks (FTIR, 1400–1500 cm−1) indicated that the larger the AOT solubilized water pools, the greater the CPA dissociation. 1 also reacted with the α-NH2 group of l-lysine (4) in AOT reverse micelles in heptane to give the corresponding Schiff base 6. Protonation of 6 occurred either intramolecularly or by reaction with unreacted 4. These results were discussed in terms of rhodopsin protonations. Keywords: retinylidene Schiff bases, reverse micelles, protonation of Schiff bases, trans to cis photoisomerization.