- Preparation method of (2-carboxyethyl) dimethyl sulfonium chloride
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The invention belongs to the technical field of feed additives, and particularly relates to a preparation method of (2-carboxyethyl) dimethyl sulfonium chloride, which comprises the following steps: (1) dissolving 3-bromopropionic acid in an organic solvent under stirring conditions, adding sodium methyl mercaptide, carrying out heating reaction, adding water after the reaction finishes, regulating the pH value to 5-6 with hydrochloric acid, and extracting with ethyl acetate; washing an ethyl acetate layer with water after liquid separation, and carrying out rotary evaporation to remove ethylacetate and water to obtain an intermediate 3-(methylthio) propionic acid; and (2) under a stirring condition, adding the intermediate 3-(methylthio) propionic acid synthesized in the step (1) into ethyl acetate, cooling to below 2 DEG C in an ice bath, introducing chloromethane to react, carrying out suction filtration and drying after the reaction is finished to obtain a 2-(carboxyethyl) dimethyl sulfonium bromide crude product, and recrystallizing with absolute ethyl alcohol to obtain the target product (2-carboxyethyl) dimethyl sulfonium chloride. The method is environmentally friendly andeasier to operate, the yield of the synthesized (2-carboxyethyl) dimethyl sulfonium chloride is high, a foul smell pollution production process is abandoned, and the body health of production personnel is guaranteed.
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Paragraph 0017-0019
(2021/01/11)
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- Simple method for preparing 3-methylthiopropionic acid
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The invention relates to a simple method for preparing 3-methylthiopropionic acid. The method comprises taking acrylic acid and sodium methyl mercaptide as raw materials for reaction in alkaline aqueous solution at 30-60 DEG C for 2-5, performing acidification by concentrated sulfuric acid and extraction by organic solvent to separate out organic phase, and performing normal-temperature distillation to recover the solvent and reduced-pressure distillation to obtain the 3-methylthiopropionic acid. The simple method for preparing the 3-methylthiopropionic acid is low in cost, simple in operation, high in yield and purity of prepared products and applicable to industrial production.
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Paragraph 0013; 0016; 0018
(2019/05/02)
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- Chemical differentiation of three DMSP lyases from the marine: Roseobacter group
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Dimethylsulfoniopropionate (DMSP) catabolism of marine bacteria plays an important role in marine and global ecology. The genome of Ruegeria pomeroyi DSS-3, a model organism from the Roseobacter group, harbours no less than three genes for different DMSP lyases (DddW, DddP and DddQ) that catalyse the degradation of DMSP to dimethyl sulfide (DMS) and acrylate. Despite their apparent similar function these enzymes show no significant overall sequence identity. In this work DddQ and DddW from R. pomeroyi and the DddP homolog from Phaeobacter inhibens DSM 17395 were functionally characterised and their substrate scope was tested using several synthetic DMSP analogues. Comparative kinetic assays revealed differences in the conversion of DMSP and its analogues in terms of selectivity and overall velocity, giving additional insights into the molecular mechanisms of DMSP lyases and into their putatively different biological functions.
- Burkhardt, Immo,Lauterbach, Lukas,Brock, Nelson L.,Dickschat, Jeroen S.
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supporting information
p. 4432 - 4439
(2017/07/10)
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- New phthalimide-methionine dyad-based fluorescence probes for reactive oxygen species: Singlet oxygen, hydrogen peroxide, and hypochlorite
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Different reactive oxygen species were detected by the molecular probes 1-3 that were composed of the phthalimide fluorophore as reporter and a methionine-derived thioether side-chain as receptor part. The sulfoxides that were formed as the primary oxidation products show strong fluorescence in the blue-green (430-540?nm) spectral region. Self-sensitized oxidation by singlet oxygen is in general inefficient indicating rapid electron-transfer quenching of the excited probe molecules. With hydrogen peroxide as thermal oxidant conversion to the sulfoxides is slow but can be accelerated by addition of titanium(IV) catalysts, whereas hypochlorite as oxidant behaves much more reactive even under uncatalyzed conditions. Singlet oxygen that is generated by energy transfer from the photosensitizer Rose Bengal was detected by sensor 1a with rate constants of >107M–1?s–1, a typical rate constant for the oxidation of thioethers to sulfoxides.
- Griesbeck, Axel G.,?ngel, Banu,Atar, Murat
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- ONIUM SALT, LIQUID COMPOSITION CONTAINING SAID ONIUM SALT AND CELLULOSE, AND CELLULOSE RECOVERY METHOD
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The invention relates to an onium salt, a liquid composition containing the onium salt and cellulose, and a method for recovering cellulose. The invention makes it possible to provide an onium salt having an extremely high ability to dissolve cellulose at temperatures of 100° C. or lower. It also makes it possible to provide a liquid composition containing this onium salt and cellulose, as a composition suitable for the recovery of cellulose, and a method for recovering cellulose efficiently by using such a liquid composition containing the onium salt and cellulose.
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Paragraph 0125; 0126; 0127
(2016/02/19)
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- Studies on umami taste. Synthesis of new guanosine 5′-phosphate derivatives and their synergistic effect with monosodium glutamate
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A number of N2-alkyl and N2-acyl derivatives of guanosine 5′-phosphate (GMP) have been synthesized and tested for their synergistic effect with monosodium L-glutamate (MSG), the prototypical substance imparting umami taste to savory-based foods. Capacities to enhance the taste intensity of MSG (γ values) were estimated through subjective comparisons of MSG/nucleotide mixtures in water with appropriate solutions of MSG alone. Assuming β = γ[nucleotide]/γ[IMP], β values of the N 2-substituted GMPs were found in the range 1.2-5.7. Such values appear to be related to the chain length of the substituent in the 2-position of the purine nucleus and dependent on the replacement of a CH2 group with an S atom and/or with an α-CO group. These findings indicate that the exocyclic NHR group of the guanine moiety is actively implicated in the synergism between GMP derivatives and MSG. Theoretical calculations suggest that an anti conformation is probably assumed by ribonucleotide molecules interacting with umami receptors.
- Cairoli, Paola,Morelli, Carlo F.,Speranza, Giovanna,Manitto, Paolo,Pieraccini, Stefano,Sironi, Maurizio
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supporting information; experimental part
p. 1043 - 1050
(2009/05/08)
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- A mild hydrolysis of esters mediated by lithium salts
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When treated with amine bases such as triethylamine and various lithium salts in wet solvents, esters are efficiently hydrolyzed to the corresponding acids in good yields. Esters incorporating an α- or β-heteroatom with respect to the ester carbonyl group are hydrolyzed rapidly even at room temperature. To further demonstrate the usefulness of this method, one example is provided where hydrolysis of acetylated camphorsultam is mediated by LiBr.
- Mattsson, Sara,Dahlstr?m, Mikael,Karlsson, Staffan
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p. 2497 - 2499
(2007/10/03)
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- Design of potent inhibitors of human β-secretase. Part 1
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We describe a novel series of potent inhibitors of human β-secretase. These compounds possess the hydroxyethyl amine transition state isostere. A 2.5 A crystal structure of inhibitor 32 bound to BACE is provided.
- Freskos, John N.,Fobian, Yvette M.,Benson, Timothy E.,Bienkowski, Michael J.,Brown, David L.,Emmons, Thomas L.,Heintz, Robert,Laborde, Alice,McDonald, Joseph J.,Mischke, Brent V.,Molyneaux, John M.,Moon, Joseph B.,Mullins, Patrick B.,Bryan Prince,Paddock, Donna J.,Tomasselli, Alfredo G.,Winterrowd, Gregory
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- Synthesis of sulfur-containing tricyclic ring systems by means of photoinduced decarboxylative cyclizations
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The intramolecular and intermolecular photoinduced electron transfer reactions of a series of mercaptoacetic acid and mercaptopropionic acid derivatives were investigated. In the intermolecular series, the phthalimidoalkylsulfanylalkylcarboxylates 1a-j and 2 were transformed into the tricyclic ring systems 3a-j and 4, respectively, with high regioselectivities. The mercaptoacetic acid and 2-mercaptopropionic acid derived substrates 1a-g and 2 readily cyclized in good to excellent yields (60-98%) but with low diastereoselectivities (except for 1d), whereas the corresponding 3-mercaptopropionic acid derived substrates 1h-j gave the corresponding tricyclic products 3h-j after prolonged irradiation, but with poor yields (11-20%). The intermolecular version - i.e., photodecarboxylative addition to N-methylphthalimide (5) as electron acceptor - was successful with mercaptoacetic acid, and 2-mercaptopropionic acid substrates 6a-c and the addition products 7a-c were obtained in high yields (57-90%). No addition, however, was observed with 3-(methylsulfanyl)propionic acid (6d). The regioselectivity of decarboxylation proceeded in a controlled manner for the mercaptosuccinic acid derivatives in both the intramolecular (with 8a-c) and the intermolecular (with 9) versions. Comparison between sulfur-activated and nonactivated species (13, 15) or irradiation of la under nonactivating conditions showed that the carboxylate anion in the position ct to the electron-donating sulfur atom acts as a superior leaving group. This efficiency is drastically reduced for carboxylate anions in the β position. With the former substrates, the photochemical cyclization proceeds with high product yields. Quantum yield measurements for decomposition (Φd as a measure for cyclization) supported these observations. CV measurements indicated preorientation prior to electron transfer in the intramolecular pathway.
- Griesbeck, Axel G.,Oelgemoeller, Michael,Lex, Johann,Haeuseler, Andreas,Schmittel, Michael
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p. 1831 - 1843
(2007/10/03)
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- 'Chemical co-substrate rescue' of phytanoyl-CoA 2-hydroxylase mutants causing refsum's disease
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The in vitro catalytic activity of two clinically observed mutants of phytanoyl-CoA 2-hydroxylase, an iron(II)/2-oxoglutarate-dependent oxygenase causing Refsum's Disease, was partially rescued by the use of alternatives to the natural cosubstrate, 2-oxoglutarate; this is the first demonstration of 'chemical co-substrate rescue' of mutations to an enzyme causing human disease.
- Mukherji,Kershaw,MacKinnon,Clifton,Wierzbicki,Schofield,Lloyd
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p. 972 - 973
(2007/10/03)
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- Decarboxylative photoadditions of heteroatom-substituted carboxylates to phthalimides
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α-Thioalkyl and α-oxoalkyl-substituted potassium carboxylates efficiently decarboxylate in the presence of electronically excited phthalimides. Radical coupling and reduction products result from secondary steps. In contrast, β-thioalkyl-substituted carboxylates are unreactive under the reaction conditions whereas β-oxoalkyl-substituted carboxylates react quantitatively. This behaviour is rationalized by assuming primary photoinduced electron transfer with sulfur oxidation, respectively, and no oxidation of the ether oxygen. In β-thioalkyl-substituted carboxylates, the thioether radical cation serves as hole trap and prevents the carboxylate of oxidative cleavage.
- Griesbeck, Axel G.,Oelgem?ller, Michael
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- A mechanistic rationalisation for the substrate specificity of recombinant mammalian 4-hydroxyphenylpyruvate dioxygenase (4-HPPD)
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The isolation and purification of α-ketoisocaproate dioxygenase [α-KICD] from rat liver is described. Sequence determination of the purified protein revealed it to have complete homology to rat liver 4-hydroxyphenylpyruvate dioxygenase [4-HPPD] which was confirmed by the cloning and expression of the gene encoding 4-HPPD in E. coli. Examination of the substrate specificity of the resulting soluble recombinant protein revealed it to be capable of the oxidative decarboxylation of a range of ketoacids derived from proteinogenic amino acids. The significance of the turnover of these different ketoacids is discussed in relation to the mechanism of this fascinating enzyme.
- Crouch, Nicholas P.,Adlington, Robert M.,Baldwin, Jack E.,Lee, Meng -Huee,MacKinnon, Colin H.
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p. 6993 - 7010
(2007/10/03)
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- Identification and stereochemistry of the product of 4-HPPD catalyzed oxidation of the ketoacid of methionine
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4-Hydroxyphenylpyruvate dioxygenase catalyzes the conversion of 2-oxo-5-thiahexanoic acid 1, the ketoacid from methionine to an unequal mixture of 4-thiapentanoic acid-4-oxide enantiomers 2a.
- Adlington, Robert M.,Baldwin, Jack E.,Crouch, Nicholas P.,Lee, Meng-Huee,MacKinnon, Colin H.
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p. 2003 - 2006
(2007/10/03)
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- Cisplatin Analogues with Sulfur Donor Ligands. (Ethylenediamine)platinum(II) Complexes with Ligands possessing a Sulfinyl or Sulfanyl Group linked to an Anionic Oxygen Donor Atom. Reactivity and Cytotoxicity
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Complexes of formula NO3, where en = ethylenediamine and L is a ligand in which a methylsulfinyl or methylsulfanyl group is linked to a carboxylate or phenolate moiety, have been synthesized and characterized by spectroscopic techniques.The ligand L is chelated to Pt via the sulfur and anionic oxygen atoms.The reactivities of these complexes towards nucleophiles have been investigated by 1H NMR spectroscopy; GMP is more reactive than Cl(-).The Pt-O bonds react more readily than the Pt-S bonds and, depending on the nature of L and Nu, the reactions either stop at the monosubstituted complex (with L monodentate and co-ordinated to Pt via the sulfur atom), or yield .The complex with L = 2-(methylsulfanyl)phenolate is unreactive.The stable monosubstituted products have been characterized.There is little correlation between the rates and the modes of reactivity of complex NO3 towards GMP and their cytotoxicities against the human ovarian carcinoma A2780 cell line.
- Pasini, Alessandro,Perego, Paola,Balconi, Massimo,Lupatini, Mauro
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p. 579 - 586
(2007/10/02)
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- Neighboring Group Participation in Radicals: Pulse Radiolysis Studies on Radicals with Sulfur-Oxygen Interaction
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Neighboring group participation by alcohol and carboxylate groups resulting in kinetic and thermodynamic stabilization of an oxidized sulfur atom in various organic sulfides is reported.The resulting radical intermediates of the general type are characterized by an optical absorption in the 400-nm range and exhibit lifetimes of up to several hundred microseconds in aqueous solution under pulse radiolysis conditions.Significant sulfur-oxygen interaction seems to occur, however, only if both heteroatoms are separated by three or four carbon atoms in the unoxidiz ed molecule which enables favorable five- or six-membered ring structures in the radical intermediates.This geometric effect can additionally be favored by minimizing the free rotation of the functional groups through rigid molecular structures, e.g., in norbornane derivatives, and introduction of particular substituents.A most suitable function for stabilization of an oxidized sulfur atom seems to be a carboxylate group where an overall radical of the general structure is formed.In these species stabilization can be envisaged to involve the carboxylate group as a whole rather than only an individual oxygen atom.The bond strength of the sulfur-carboxylate interaction is estimated to be of the order of 50 kJ mol-1 as deduced from the temperature dependence of its dissociation.Further evidence for net sulfur-carboxylate bonding is provided by rate constants of 105-107 M-1s-1 for its proton-assisted decay.These rates are considerably lower than for the diffusion controlled protonation of free carboxylate functions.Oxidation of endo-2-(2-hydroxyisopropyl)-endo-6-(methylthio)bicycloheptane yields a transient where sulfur-oxygen interaction is associated with a strong acidification of the alcoholic hydroxyl group.A pK = 5.9 has been measured for the equilibrium.All the results on these transient radical intermediates can be viewed in terms of neighboring group participation.Such participation is also clearly evidenced in the formation and properties of intermolecular radical cations, , derived from these sulfides, and in the kinetics of the primary oxidation proces.Absolute rate constants for the one-electron oxidation of various sulfides by CCl3OO. radicals, for example, have been found to range from 3*108 to -6 M-1 s-1 depending on the nature of the oxygen containing functional groups.The present results are finally discussed in terms of the general possibility of stabilization of an oxidized sulfur function by other heteroatoms.Several electronic structures including the two-center-three (2?/1?*) electron bond can be advanced to describe the physicochemical properties of the radicals with sulfur-oxygen interaction.
- Mahling, Sabine,Asmus, Klaus-Dieter,Glass, Richard S.,Hojjatie, Massoud,Wilson, George S.
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p. 3717 - 3724
(2007/10/02)
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- Process for the production of 1,2-dithiolan-3-pentanoic acid (thioctic acid) and intermediate compounds therefor
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1,2-Dithiolane-3-pentanoic acid (D,L-thioctic acid) of the formula STR1 is prepared by a process comprising (a) reacting a 2-(3-alkylthiopropionyl)-cyclopentanone-1 of the formula STR2 where R is a C1 -C4 alkyl, phenyl or benzyl in aqueous alkaline solution at a temperature of about 20° C. to about 90° C. to form the corresponding carboxylic acid of formula VI STR3 (b) reacting the compound of formula VI with an alkyl mercaptan at a temperature between -20° C. and 0° C. to form the corresponding thioketal of formula VII STR4 (c) reacting the compound of formula VII with sodium in liquid ammonia at a temperature between -60° C. and -10° C. to form the 6,8-dimercaptooctanoic acid of formula VIII STR5 (d) reacting the 6,8-dimercaptooctanoic acid of formula VIII in alkaline solution with an iron (III) salt and oxygen to form the 1,2-dithiolane-3-pentanoic acid of formula IX, or in place of steps (a) through (c) reacting an acid of formula XII STR6 where R1 and R2 are hydrogen, C1 -C4 -alkyl, phenyl or benzyl, with the proviso that both R1 and R2 cannot be benzyl, with sodium in liquid ammonia at a temperature between -60° C. and -10° C. to form the corresponding 6,8-dimercaptooctanoic acid of formula VIII. The compounds of formulae VI, VII, XII are new.
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- MgBr2-Promoted Addition of Heterosubstituted Methylketene Silyl Acetals to Alkoxy Aldehydes. Diastereoselective Synthesis of 3,4-Syn 2-Methylene- and 2-(Alkoxymethyl)-3-hydroxy-4-alkoxy Esters
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The MgBr2-mediated addition of 2- or 3-(methylthio)-substituted ketene silyl acetals 3 and 4 to α-alkoxy and α,β-dialkoxy aldehydes, followed by oxidation and elimination of methanesulfenic acid, gave 3,4-syn 2-methylene-3-hydroxy-4-alkoxy esters 9 and 11 with very high stereoselectivity (up to 100:1) and in good chemical yields.The same diastereofacial selection is at work in the analogous additions of ketene methyl silyl acetal 5, which affords 3,4-syn 2--3-hydroxy-4-alkoxy esters 12-15.
- Bernardi, Anna,Cardani, Silvia,Colombo, Lino,Poli, Giovanni,Schimperna, Giuliana,Scolastico, Carlo
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p. 888 - 891
(2007/10/02)
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- Neighboring Group Participation in Organic Redox Reactions. 11. Anchimeric Assistance by the Carboxylate Anion in Aqueous Iodine Oxidations of 3-(Alkylthio)propanoates
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The kinetics and mechanism of the aqueous iodine oxidation of three 3-(alkylthio)propanoates has been examined in detail.All the oxidations are essentially independent of external buffer and proceed via anchimeric assistance by the carboxylate anion.The reaction of aqueous iodine with both 3,3'-thiodipropanoate and 3-(methylthio)propanoate are enhanced a millionfold over that of simple thioethers, making these thioethers among the most easily oxidized of any reported.The degree of anchimeric assistance is considerably less with N-acetyl-S-methylcysteinate and is attributable to the lowered basicity of its carboxylate group.
- Doi, Joyce Takahashi,Goodrow, Marvin H.,Musker, W. Kenneth
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p. 1026 - 1029
(2007/10/02)
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- S,S-Dialkyl Dithiocarbonates as a Convenient Source of Alkanethiols: an Improved Synthesis of Alkylthiocarboxylic Acids
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A wide variety of β-alkylthiocarboxylic acids are obtained by addition of alkanethiols - generated in situ from S,S-dialkyl dithiocarbonates - to appropriate α,β-unsaturated carboxylic acids in good to excellent yields.
- Cadamuro, Silvano,Degani, Iacopo,Fochi, Rita,Regondi, Valeria
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p. 1070 - 1074
(2007/10/02)
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- Diastereospecific, Enzymically Catalysed Transmethylation from S-Methyl-L-methionine to L-Homocysteine, a Naturally Occuring Process
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A known catabolic pathway of S-methyl-L-methionine in higher plants: donation of a methyl group to L-homocysteine resulting in the production of two molecules of L-methionine, is subjected to stereochemical studies.The two, diastereoisomeric (2-2H, methyl-13C)-S-methyl-L-methionines are synthesized and utilised in transmethylation reactions with L-homocysteine as the acceptor and an enzyme preparation from jack beans as a catalyst.The resulting, variously labelled methionine species are converted into butyl esters of the N-trifluoroacetylated derivatives and, as such, subjected to g.l.c. combined with mass spectrometry in two ionisation modes.Experimentally determined parameters such as mass peack intensities, isotopic enrichment factors, diastereoisomeric purities, and protein-derived methionine, are utilised for calculating the stereoselectivity in the enzyme transfer of the diastereoisotopic methyl groups from S-methyl-L-methionine to L-homocysteine.Together, the independent results from the two series of diastereoisomers reveal an enzymatic preference of the pro-(R)-methyl group to the extent of 94percent or more.
- Grue-Soerensen, Gunnar,Kelstrup, Ebbe,Kjaer, Anders,Madsen, Joergen Oegaard
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p. 1091 - 1097
(2007/10/02)
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