- Mechanistic studies of 1-aminocyclopropane-1-carboxylate deaminase: Characterization of an unusual pyridoxal 5′-phosphate-dependent reaction
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1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase (ACCD) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that cleaves the cyclopropane ring of ACC, to give α-ketobutyric acid and ammonia as products. The cleavage of the Cα-Cβ bond of an amino acid substrate is a rare event in PLP-dependent enzyme catalysis. Potential chemical mechanisms involving nucleophile- or acid-catalyzed cyclopropane ring opening have been proposed for the unusual transformation catalyzed by ACCD, but the actual mode of cyclopropane ring cleavage remains obscure. In this report, we aim to elucidate the mechanistic features of ACCD catalysis by investigating the kinetic properties of ACCD from Pseudomonas sp. ACP and several of its mutant enzymes. Our studies suggest that the pKa of the conserved active site residue, Tyr294, is lowered by a hydrogen bonding interaction with a second conserved residue, Tyr268. This allows Tyr294 to deprotonate the incoming amino group of ACC to initiate the aldimine exchange reaction between ACC and the PLP coenzyme and also likely helps to activate Tyr294 for a role as a nucleophile to attack and cleave the cyclopropane ring of the substrate. In addition, solvent kinetic isotope effect (KIE), proton inventory, and 13C KIE studies of the wild type enzyme suggest that the Cα-C β bond cleavage step in the chemical mechanism is at least partially rate-limiting under kcat/Km conditions and is likely preceded in the mechanism by a partially rate-limiting step involving the conversion of a stable gem-diamine intermediate into a reactive external aldimine intermediate that is poised for cyclopropane ring cleavage. When viewed within the context of previous mechanistic and structural studies of ACCD enzymes, our studies are most consistent with a mode of cyclopropane ring cleavage involving nucleophilic catalysis by Tyr294.
- Thibodeaux, Christopher J.,Liu, Hung-Wen
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- Structural elucidation of aculeximycin. III. Planar structure of aculeximycin, belonging to a new class of macrolide antibiotics
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The planar structure of aculeximycin (1) produced by Streptosporangium albidum has been determined by spectral methods and chemical degradations such as 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU)-methanol reaction, ozonolysis, and periodative oxidation. The antibiotic consists of a 30-membered polyhydroxy lactone ring, α or, β-unsaturated ester group, an intramolecular hemiketal, an oligosaccharide (aculexitriose), a neutral sugar and an amino sugar. The structure of aculeximycin is closely related to those of sporaviridins produced by Streptosporangium viridogriseum. We consider that aculeximycin and sporaviridins belong to a new class of macrolide antibiotics, which is different from the polyol macrolides produced by Streptomyces.
- Murata,Suzuki,Tabayashi,Hattori,Takada,Harada,Suzuki,Ikemoto,Shibuya,Haneishi,Torikata,Itezono,Nakayama
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Read Online
- Synthesis of Dicarboxylic Acids from Aqueous Solutions of Diols with Hydrogen Evolution Catalyzed by an Iridium Complex
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A catalytic system for the synthesis of dicarboxylic acids from aqueous solutions of diols accompanied by the evolution of hydrogen was developed. An iridium complex bearing a functional bipyridonate ligand with N,N-dimethylamino substituents exhibited a high catalytic performance for this type of dehydrogenative reaction. For example, adipic acid was synthesized from an aqueous solution of 1,6-hexanediol in 97 % yield accompanied by the evolution of four equivalents of hydrogen by the present catalytic system. It should be noted that the simultaneous production of industrially important dicarboxylic acids and hydrogen, which is useful as an energy carrier, was achieved. In addition, the selective dehydrogenative oxidation of vicinal diols to give α-hydroxycarboxylic acids was also accomplished.
- Fujita, Ken-ichi,Toyooka, Genki
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- PtII-Catalyzed Hydroxylation of Terminal Aliphatic C(sp3)?H Bonds with Molecular Oxygen
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The practical application of Shilov-type Pt catalysis to the selective hydroxylation of terminal aliphatic C?H bonds remains a formidable challenge, due to difficulties in replacing PtIV with a more economically viable oxidant, particularly O2. We report the potential of employing FeCl2 as a suitable redox mediator to overcome the kinetic hurdles related to the direct use of O2 in the Pt reoxidation. For the selective conversion of butyric acid to γ-hydroxybutyric acid (GHB), a significantly enhanced catalyst activity and stability (turnover numbers (TON)>30) were achieved under 20 bar O2 in comparison to current state-of-the-art systems (TON0 was prevented by the addition of monodentate pyridine derivatives, such as 2-fluoropyridine, but also by introducing varying partial pressures of N2 in the gaseous atmosphere. Finally, stability tests revealed the involvement of PtII and FeCl2 in catalyzing the non-selective overoxidation of GHB. Accordingly, in situ esterification with boric acid proved to be a suitable strategy to maintain enhanced selectivities at much higher conversions (TON>60). Altogether, a useful catalytic system for the selective hydroxylation of primary aliphatic C?H bonds with O2 is presented.
- Janssen, Michiel,De Vos, Dirk E.
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supporting information
p. 10724 - 10734
(2019/07/15)
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- Antioxidant Properties of Heterocyclic Intermediates of the Maillard Reaction and Structurally Related Compounds
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It is well established that a wide range of reductones is formed in the course of the Maillard reaction and that these substances contribute to the oxidative stability of food. The aim of this study was to analyze 12 important heterocyclic intermediates with and without reductone structure as well as structurally related substances under equal conditions to compare their antioxidant properties in detail. For this purpose, five methods were selected including photometrical methods such as the trolox equivalent antioxidant capacity assay and an electron paramagnetic resonance spectroscopic method. Reductones with furan-3-one structure and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one were reducing in all assays, whereas isomaltol and maltol did not react in assays based on the reduction of metal ions because of their complexing abilities. The introduction of protecting groups to the free hydroxyl functions of selected reductones could nearly eliminate their reducing abilities. In addition, the oxidation products of the different reductive heterocycles were compared after treatment with iodine. Mainly short-chained organic acids such as lactic, glycolic, and glyceric acid are formed as result of the degradation, which indicates 1,3-dicarbonyl cleavage reactions of corresponding tricarbonyl compounds as intermediates of the oxidation.
- Kanzler, Clemens,Haase, Paul T.,Schestkowa, Helena,Kroh, Lothar W.
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p. 7829 - 7837
(2016/10/31)
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- PROCESSES FOR PREPARATION OF IDELALISIB AND INTERMEDIATES THEREOF
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The present application provides processes for preparation of Idelalisib and intermediates thereof. The present application also provides a process for purification of Idelalisib.
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Page/Page column 34; 35
(2016/07/27)
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- PROCESSES FOR CONVERSION OF BIOLOGICALLY DERIVED MEVALONIC ACID
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The invention relates to a process comprising reacting mevalonic acid, or a solution comprising mevalonic acid, to yield a first product or first product mixture, optionally in the presence of a solid catalyst and/or at elevated temperature and/or pressure. The invention further relates to a process comprising: (a) providing a microbial organism that expresses a biosynthetic mevalonic acid pathway; (b) growing the microbial organism in fermentation medium comprising suitable carbon substrates, whereby biobased mevalonic acid is produced; and (c) reacting said biobased mevalonic acid to yield a first product or first product mixture.
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Paragraph 0095-0103
(2016/06/13)
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- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
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The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 6055 - 6058
(2014/12/10)
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- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
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The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 6055 - 6058
(2015/03/30)
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- Chemical conversion of sugars to lactic acid by alkaline hydrothermal processes
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Some like it hot: Lactic acid is an important commodity chemical that is mainly used in the food industry or for the manufacture of biodegradable plastics. A highly efficient strategy for the conversion of carbohydrates from biomass to lactic acid through alkaline hydrolysis in superheated water is presented. Copyright
- Esposito, Davide,Antonietti, Markus
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p. 989 - 992
(2013/07/27)
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- METHOD FOR SYNTHESIS OF KETO ACID OR AMINO ACID BY HYDRATION OF ACETHYLENE COMPOUND
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An object of the present invention is to provide a method for synthesis of keto acids by hydration of an acetylene compound (acetylene-carboxylic acids) under mild conditions free from harmful mercury catalysts and a method for synthesis of amino acids from acetylene-carboxylic acids in a single container (one-pot or tandem synthesis). In one embodiment of the method according to the present invention for synthesis of keto acids, acetylene-carboxylic acids is hydrated in the presence of a metal salt represented by General Formula (1), where M1 represents an element in Group VIII, IX, or X of the periodic table, and X1, X2, or X3 ligand represents halogen, H2O, or a solvent molecule, and k represents a valence of a cation species, and Y represents an anion species, and L represents a valence of the anion species, and each of K and L independently represents 1 or 2, and k × m = L × n.
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Page/Page column 23-24
(2008/12/06)
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- Method and product for skin lightening
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A method and cosmetic product for lightening skin is provided, the method including wiping the skin with a cosmetic towelette. Impregnated on the towelette is an alpha-hydroxy carboxylic acid or salt thereof and a sunscreen agent.
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- An inexpensive carbohydrate derivative used as a chiral auxiliary in the synthesis of α-hydroxy carboxylic acids
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Protected α-hydroxy carboxylic acids were synthesized in moderate yield and high diastereoselectivity by alkylation of glycolate (α-hydroxy acetate) enolates using a D-fructose-derived chiral auxiliary. The new chiral center was assigned the R configuration based on comparisons of optical rotations and on one crystal structure analysis. This alkylation methodology is compatible with several hydroxyl protecting groups. The free hydroxy acids were obtained upon removal of the protecting group from the hydroxyl functionality followed by saponification.
- Yu, Hongwu,Ballard, C.Eric,Boyle, Paul D,Wang, Binghe
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p. 7663 - 7679
(2007/10/03)
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- Towelette product
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A disposable towelette product is provided which includes a flexible water-insoluble substrate such as a tissue impregnated with an alpha- or beta-hydroxycarboxylic acid in a cosmetically acceptable carrier vehicle. Impregnated cosmetic composition in water will have a pH no higher than 6.8. A silicone microemulsion is present to minimize any stickiness resulting from deposition of the hydroxycarboxylic acid by the towelette onto the skin. In the presence of fatty acid group containing surfactants, the silicone microemulsion controls foul odors that the surfactants may emit through hydrolysis at low pH.
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- Towelette product for minimizing facial fine lines and wrinkles
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A disposable towelette is provided which includes a flexible substrate such as a cellulosic tissue impregnated with an alpha-hydroxycarboxylic add delivered in a cosmetically acceptable carrier vehicle. There is further provided a method for cleansing skin and simultaneously inhibiting fine lines and wrinkles by wiping the skin with the impregnated towelette.
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- Processes for producing alpha -cyanohydrin esters and alpha -hydroxy acids
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In the presence of a metal catalyst such as a samarium compound, an enol ester compound shown by the formula (1) is reacted with a carbonyl compound shown by the formula (3) and a cyanogenation agent to produce an alpha -cyanohydrin ester shown by the formula (4): wherein R1, R7, and R8 are the same or different from each other, each representing a non-reactive atom or a non-reactive organic group; R2, R3, and R4 are the same or different from each other, each representing a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. By hydrolyzing the obtained compound, the corresponding alpha -hydroxy acid or a salt thereof can be obtained. According to the above processes, an alpha -cyanohydrin ester and an alpha -hydroxy acid can be obtained in high yields.
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- SHORT CHAIN 2-HYDROXYCARBOXYLIC ACID-BASED DERIVATIVES OF CERAMIDES
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The present invention relates to active ceramide derivatives. Specifically, the invention relates to 2(alpha)-hydroxycarboxylic acid-based ceramide derivatives. The present invention describes a method for obtaining these compounds. The invention also relates to the use of these compounds in cosmetic compositions.
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- Compositions and methods for enhancing the topical effects of sunscreen agents
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Uses of topical compositions comprising a 2-hydroxycarboxylic acid or related compound to alleviate or improve signs of skin, nail and hair changes associated with intrinsic or extrinsic aging are disclosed. 2-Hydroxycarboxylic acids and their related compounds include, for example, 2-hydroxyethanoic acid, 2-hydroxypropanoic acid, 2-methyl 2-hydroxypropanoic acid, 2-phenyl 2-hydroxyethanoic acid, 2-phenyl 2-methyl 2-hydroxyethanoic acid, 2-phenyl 3-hydroxypropanoic acid, 2,2-diphenyl 2-hydroxyethanoic acid, 2-hydroxybutane-1,4-dioicacid, 2,3-hihydroxybutane-1,4-dioic acid, 2-carboxy 2-hydroxypentane-1,5-dioic acid, 2-ketopropanoic acid, methyl 2-ketopropanoate, ethyl 2-ketopropanoate, and gluconolactone. Topical application of compositions comprising 2-hydroxycarboxylic acid and/or related compounds has been found to alleviate or improve skin lines; blotches; blemishes; nodules; wrinkles; pigmented spots; atrophy; precancerous lesions; elastotic changes characterized by leathery, coarse, rough, dry and yellowish skin; and other skin changes associated with intrinsic aging or skin damages caused by extrinsic factors such as sunlight, radiations, air pollution, wind, cold, dampness, heat, chemicals, smoke and cigarette smoking. Topical applications of such compositions have also been found to improve the overall qualities of nail and hair affected by intrinsic aging or damaged by extrinsic factors.
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- Anhydrous cosmetic composition with ceramides for firming skin
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A method and cosmetic composition for improving skin firmness are provided through an anhydrous composition including a hydrophobic carrier which may be a silicone or hydrocarbon for delivering an effective amount of a ceramide formed of a sphingoid base linked through an amide to a 2-hydroxycarboxylic C2-C30group.
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- Esters of L-carnitine and acyl L-carnitine with hydoxy acids for producing pharmcaeutical compositions for treating dermatoses
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Dermatosis is treated by a method comprising topically applying an effective amount of an ester of L-carnitine or an acyl L-carnitine with a hydroxy carboxylic acid selected from the group consisting of α-hydroxybutyric acid, α-hydroxyisocaproic acid, α-hydroxyisovaleric acid, malic acid and tartronic acid, to a patient in need thereof.
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- Cosmetic compositions for reducing or preventing signs of cellulite
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The invention is directed to increasing the strength and firmness of the skin and reducing the signs of cellulite. The inventive method includes applying to the skin a composition that includes inositol phosphate, particularly phytic acid and its salts, in a cosmetically acceptable carrier.
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- Use of esters of L-carnitine and acyl L-carnitine with hydroxyacids for producing pharmaceutical compositions for treating dermatoses
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The use is disclosed of esters of L-carnitine and acyl L-carnitines with hydroxyacids for producing pharmaceutical compositions suitable to be topically applied for treating dermatoses such as ichthyosis and psoriasis.
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- Making optically active alpha-hydroxy acids or precursors
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Disclosed is a process for making an α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid which comprises (1) hydrocarboxylating an enol acylate, which has a chiral C atom that is essentially all L or all D, with CO and water or an organic hydroxyl compound, thereby producing a reaction mixture containing diastereomeric α-acyloxy acids or esters having two chiral centers and having essentially no enantiomeric pairs, (2) separating the diastereomers by conventional physical means and (3) hydrolyzing at least one of said separated diastereomers to make at least the α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid. Also disclosed is a process for making an α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid which comprises (1) hydrocarboxylating an enol acylate, the enol portion of which has a chiral C atom that is essentially all L or all D, with CO and water or an organic hydroxyl compound, thereby producing a reaction mixture containing diastereomeric α-acyloxy acids or esters having two chiral centers and having essentially no enantiomeric pairs, (2) hydrolyzing the product of (1) to make a diastereomeric mixture containing α-hydroxy acids, and (3) separating by conventional physical means from the product of (2) at least one α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid.
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- Ruthenium-catalysed reductive cleavage of allylic esters with formic acid and triethylamine. Application to short-step synthesis of α-hydroxy acids
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Ruthenium-catalysed reductive cleavage reactions of allylic carboxylates and carbonates with formic acid and triethylamine to give olefins were explored.As an application of the ruthenium-catalysed processes, a new synthetic route to α-hydroxy acids has been discovered.The reductive cleavage of allylic esters is considered to proceed through ?-allylruthenium intermediates. Key words: Ruthenium; Catalysis; Reductive cleavage; Allyl; Formic acid
- Maruyama, Yooichiroh,Sezaki, Takao,Tekawa, Masafumi,Sakamoto, Toshiaki,Shimizu, Isao,Yamamoto, Akio
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p. 257 - 264
(2007/10/02)
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- Esters of unsymmetrically 2-substituted glycolic acid dimers
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This invention concerns esters of unsymmetrically 2-substituted glycolic acid dimers, a process for their preparation and their use in the preparation of unsymmetrically 3,6-substituted 1,4-dioxane-2,5-diones.
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- Effects of Gln102Arg and Cys97Gly mutations on the structural specificity and stereospecificity of the L-lactate dehydrogenase from Bacillus stearothermophilus
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The L-lactate dehydrogenase of Bacillus stearothermophilus (BSLDH) is a thermostable enzyme with considerable potential for applications in asymmetric synthesis. An understanding of the factors controlling its structural specificity and stereospecificity is therefore of interest. In this paper the effects of Gln102 → Arg and Cys97 → Gly mutations have been evaluated. In a survey of thirteen 2-keto acids, the Q102R mutation was found to reduce the activity of BSLDH toward the reduction of RCOCOOH substrates with small or hydrophilic R groups without affecting its activity toward those with larger, hydrophobic R substituents. In addition, the mutants have a high affinity for C3- and C4-2-keto dicarboxylates. The extent of fructose 1,6-diphosphate activation of the mutant enzymes was similar to its effect on wild-type BSLDH. The mutants also retained the synthetically desirable thermostability. As a probe of the commitment of BSLDH to L stereospecificity, the Q102R mutation was introduced to allow the new 102R site to compete with Arg171 for binding of the COO- groups of the RCOCOOH substrates, which would reverse the normal RCOCOOH orientation at the active site and thereby open up the possibility of the formation of a D-2-hydroxy acid in place of the natural L product. However, L stereospecificity in 2-keto acid reduction was strictly retained by the Q102R mutants. This was confirmed by preparative-scale reductions of pyruvate and phenylpyruvate to give the corresponding L-hydroxy acids in enantiomerically pure form and by comparison of the kinetics of oxidation of L- and D-lactate and L- and D-phenyl lactate. No evidence for substrate activity for the D enantiomers of either of these was seen with WT or mutant enzymes. Some catalysis of D-malate oxidation by both WT and mutant BSLDH was observed, but the L enantiomer was still preferred to approximately the same degree in both cases. That the inability of BSLDH and its 102R mutants to catalyze D-2-hydroxy acid oxidations was not simply due to the failure of the D enantiomers to bind at the active site was established by a comparison of competitive inhibition constants for the above L- and D-hydroxy acids. CD spectroscopy showed that the Gln102 → Arg mutations were not benign but induced significant structural perturbations. Electrostatic potential contours suggest that the structural changes are partly due to long-range interactions of the positive charge of the guanidinium group of Arg102 with several other residues that form an area of negative potential adjacent to the active site. The Cys97 → Gly mutation, while inadvertent, was of interest because of the potential specificity effects arising from its location adjacent to the hinge of the flexible 98-110 loop. However, its effects on BSLDH specificity were minor.
- Kallwass, Helmut K. W.,Luyten, Marcel A.,Parris, Wendy,Gold, Marvin,Kay, Cyril M.,Bryan Jones
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p. 4551 - 4557
(2007/10/02)
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- Facile Synthesis of α-Hydroxycarboxylic Acids by Ruthenium-Catalyzed Reduction od Diaalyl α-Oxalylcarboxylates with Formic Acid
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Reaction of diallyl α-oxalylcarboxylates with catalytic amounts of ruthenium complexes gave α-hydroxycarboxylic acids in good yields.
- Shimizu, Isao,Tekawa, Masafumi,Maruyama, Yooichiroh,Yamamoto, Akio
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p. 1365 - 1366
(2007/10/02)
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- An Evaluation of the Substrate Specificity, and of Its Modification by Site-Directed Mutagenesis, of the Cloned L-Lactate Dehydrogenase from Bacillus stearothermophilus
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The L-lactate dehydrogenase of Bacillus stearothermophilus (BSLDH) is a stable, thermophilic oxidoreductase.It has been selected as a model of enzymes with considerable future promise in assymetric synthesis in that it has been cloned to ensure a plentiful and inexpensive supply and because of the potential for tailoring its specificity to accept unnatural substrate structures via the site-directed mutagenesis techniques of moleculer biology.In this study, the specificity of BSLDH toward representative α-keto acids possessing straight- and branched-chain alkyl,cycloalkyl, or aromatic side chains has been evaluated.The results show that substrates that are sterically bulky in the region of the α-keto group to be reduced are poorly accepted by the enzyme.Graphics analyses indicated that the low activities of these hindered substrates might be partly due to a bad interaction of the active site residue Gln102 with large or branched substituents adjacent to the α-keto group.Accordingly, Gln102 has been replaced by the smaller Asn residue by site-directed mutagenesis in an attempt to expand the active site volume available to receive substrates larger than the natural pyruvate.However, the kinetic data show that bulky α-keto acids are only marginally better accommodated by the Gln102 -> Asn mutant than by the wild-type enzyme.
- Luyten, Marcel A.,Bur, Daniel,Wynn, Hla,Parris, Wendy,Glod, Marvin,et al.
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p. 6800 - 6804
(2007/10/02)
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- Method of making a diastereomeric mixture containing two diastereomeric α-acyloxy acid esters
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In the process of hydrocarboxylating an enol acylate with CO and an organic hydroxyl compound to produce an α-acyloxy acid ester, the improvement comprising using as the organic hydroxyl compound reactant, an organic hydroxyl compound which has a chiral center that is essentially all L or D, thereby producing a reaction mixture having essentially no enantiomeric pairs and containing diastereomeric α-acyloxy acid esters having two chiral centers.
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- AN INVESTIGATION OF THE TRANSFORMATIONS OF 2-AMINO-2-THIAZOLIN-4-ONE AND ITS DERIVATIVES IN AQUEOUS SOLUTIONS
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It has been shown by thin-layer radiochromatography that the action of an aqueous solution of alkali on 2-amino-2-thiazolin-4-one and its 5-alkyl derivatives leads predominantly to the opening of the ring by a mechanism similar to the opening of lactams in an alkaline medium.
- Fedoseev, V. M.,Mandrugin, A. A.,Semenenko, M. N.
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- Stereospecific Reduction of 2,3-Epoxybutanoic Acid. Synthesis of (R,R)- and (S,S)-3-Hydroxybutanoic-2-d Acid and S-tert-Butyl 3-Acetoxythiobutanoate-2-d
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Reduction of 2,3-epoxybutanoic acid (2) with sodium borodeuteride provides a stereospecific synthesis of 3-hydroxybutanoic-2-d acid (3).This route should be of general utility in stereospecific syntheses of metabolically important 3-hydroxyalkanoic acid derivatives labeled at C-2.Metal ions seem to play an important role in the relative rates of nucleophilic attack at the α- and β-carbon atoms of 2.Compound 3 was converted to S-tert-butyl 3-acetoxythiobutanoate-2-d (1) with virtually no H-D exchange; the mixed anhydride method proved more effective than the DCC method for the thioester synthesis.
- Mohrig, Jerry R.,Vreede, Pieter J.,Schultz, Steve C.,Fierke, Carol A.
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p. 4655 - 4658
(2007/10/02)
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