An efficient biotransformation of dialkyl esters of 2-oxoglutaric acid by Rhodotorula minuta whole cells

Whole cells of the yeast Rhodotorula minuta were used in the biotransformation of dialkyl esters of 2-oxoglutaric acid. Almost 100% of conversion with 97-98% of enantiomeric excess of the (S) form of 2-hydroxydiesters was obtained through an enantioselective reduction of dimethyl and diethyl 2-oxoglutarate. When longer alkoxy chain 2-oxoglutarates were used as substrates, the corresponding 4-hydroxybutyric esters were obtained, suggesting a combination process including hydrolysis, decarboxylation and reduction. The cells showed a remarkable high productivity: high conversion and enantiomeric excess were obtained at 2 g wet weight mmol^-1 substrate.     

An efficient biotransformation of dialkyl esters of 2-oxoglutaric acid by Rhodotorula minuta whole cells

Whole cells of the yeast Rhodotorula minuta were used in the biotransformation of dialkyl esters of 2-oxoglutaric acid. Almost 100% of conversion with 97–98% of enantiomeric excess of the (S) form of 2-hydroxydiesters was obtained through an enantioselective reduction of dimethyl and diethyl 2-oxoglutarate. When longer alkoxy chain 2-oxoglutarates were used as substrates, the corresponding 4-hydroxybutyric esters were obtained, suggesting a combination process including hydrolysis, decarboxylation and reduction. The cells showed a remarkable high productivity: high conversion and enantiomeric excess were obtained at 2 g wet weight mmol^?1 substrate.     

Metabolism of 2-chloro-4-methylphenoxyacetate by Alcaligenes eutrophus JMP 134

2-Chloro-4-methylphenoxyacetate is not a growth substrate for Alcaligenes eutrophus JMP 134 and JMP 1341. It is, however, being transformed by enzymes of 2,4-dichlorophenoxyacetic acid metabolism to 2-chloro-4-methyl-cis, cis-muconate, which is converted by enzymatic 1,4-cycloisomerization to 4-carboxymethyl-2-chloro-4-methylmuconolactone as a dead end metabolite. Chemically, only 3,6-cycloisomerization occurs, giving rise to both diastereomers of 4-carboxychloromethyl-3-methylbut-2-en-4-olide. Those lactones harbonring a chlorosubstituent on the 4-carboxymethyl side chain were surprisingly stable under physiological as well as acidic conditions.     

Direct conversion of cellulose to 1-(furan-2-yl)-2-hydroxyethanone in zinc chloride solution under microwave irradiation

Conversion of cellulose to 1-(furan-2-yl)-2-hydroxyethanone has been demonstrated in concentrated zinc chloride solution under microwave irradiation. Compared with the conventional oil-bath heating mode, microwave irradiation significantly reduced the reaction time and increased the yield of 1-(furan-2-yl)-2-hydroxyethanone. A typical degradation reaction with cellulose produced 1-(furan-2-yl)-2-hydroxyethanone in 12.0% molar yield in ZnCl₂ solution (ZnCl₂–H₂O ratio = 2.25:1, w/w) with microwave irradiation at 600 W for 5 minutes at 135 °C.     

One pot three components microwave assisted and conventional synthesis of new 3-(4-chloro-2-hydroxyphenyl)-2-(substituted) thiazolidin-4-one as antimicrobial agents

A one-pot, three-component, microwave assisted and conventional synthesis of new 3-(4-chloro-2-hydroxyphenyl)-2-(substituted) thiazolidin-4-one (4a–n) was carried out by using N,N-dimethylformamide as a solvent with high product yield. Among these synthesized compounds (4f, 4g, 4l and 4m) were found to be a broad spectrum molecule active against all bacterial and fungus strains tested, except fungus Aspergillus niger. Amongst the compounds (4g, 4l and 4m) were found to be more potent than respective standard drugs used in the experiment against Candida albicans, Staphylococcus aureus and Aspergillus flavus, respectively. All synthesized compounds were also tested for their cytotoxic activity against HeLa and MCF-7 cell lines by the sulforhodamine B (SRB) assay. This study shows that all compounds were non-cytotoxic in nature, and confirmed their antimicrobial specificity apart from any general cytotoxicity.     

Isolation and identification of (2S)-2-amino-5-chloro-4-hydroxy-5-hexenoic acid from anAmanita of the sectionRoanokenses (Amanitaceae)

A chlorine-containing non-protein amino acid which was recently discovered from the fruit bodies ofAmanita gymnopus (2S)-2-amino-5-chloro-4-hydroxy-5-hexenoic acid, was isolated and crystallized for the first time from the fruit bodies of an unknown member ofAmanita belonging to the sectionRoanokenses, subsectionSolitariae. The results of elementary analyses, determination of optical rotations,¹H- and¹³C-NMR-spectra, and some chemical reactions supported an earlier proposed structure.Part 24 in the series Biochemical studies of nitrogen compounds in fungi. for Part 23, see Hatanaka, S. I. et al. 1994. this journal35: 391–394.     

Enantioselective synthesis of (S)-2-amino-4-phenylbutanoic acid by the hydantoinase method

Biosynthesis of (S)-(+)-2-amino-4-phenylbutanoic acid (1) was performed by nonenantioselective hydantoinase and L-N-carbamoylase using racemic 5-[2-phenylethyl]-imidazolidine-2,4-dione (rac-2) as a substrate. The compounds involved in this biocatalysis process could be simultaneously resolved by high-performance liquid chromatography using Chirobiotic T column with a mobile phase of EtOH/H(2)O = 10/90 at pH 4.2-4.5. To our knowledge, this is the first report of the successful production of 1 by the combination of recombinant hydantoinase and L-N-carbamoylase.     

Some effects of 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785) on the development of chloroplast thylakoid membranes in Hordeum vulgare L.

Chloroplast ultrastructural and photochemical features were examined in 6-d-old barley (Hordeum vulgare L. cv. Sundance) plants which had developed in the presence of 4-chloro-5-(dimethylamino)-2-phenyl-3(2H)-pyridazinone (San 9785). In spite of a substantial modification of the fatty-acid composition of thylakoid lipids there were no gross abnormalities in chloroplast morphology, and normal amounts of membrane and chlorophyll were present. Fluorescence kinetics at 77K demonstrated considerable energetic interaction of photosystem (PS)I and PSII chlorophylls within the altered lipid environment. An interference with electron transport was indicated from altered room-temperature fluorescence kinetics at 20°C. Subtle changes in the arrangements of chloroplast membranes were consistently evident and the overall effects of these changes was to increase the proportion of appressed to nonappressed membranes. This correlated with a lower chlorophyll a/b ratio, an increase in the amount of light-harvesting chlorophylls as determined by gel electrophoresis and fluorescence emission spectra, and an increase in excitation-energy transfer from PSII to PSI, as predicted from current ideas on the organisation of photosystems in appressed and non-appressed thylakoid membranes.Abbreviations CP1 P700-chlorophyll a protein - F_o, F_m, F_v minimal, maximal and variable fluorescence yield - LHCP light-harvesting chlorophyll-protein complex - PSI, PSII photosystem I, II - San 9785 4-chloro-5(dimethylamino)-2-phenyl-3(2H)-pyridazinone     

Hydroxycinnamic acid esters enhance peroxidase-dependent oxidation of 3, 4-dihydroxyphenylalanine. differences in the enhancement among the esters

Horseradish peroxidase (HRP)-dependent oxidation of 3, 4-dihydroxyphenylalanine (dopa) was studied to elucidate the mechanism of its oxidation. The oxidation of dopa was enhanced by hydroxycinnamic acid esters and dopa supressed HRP-dependent oxidation of the esters. These results indicate that phenoxyl radicals of hydroxycinnamic acid esters that are formed at first, can oxidize dopa. Among hydroxycinnamic acid esters used, affinity of the phenoxyl radicals for dopa was in order 4-coumaric>caffeic>ferulic acid ester radicals.     

2-amino-4-acetylaminobutyric acid, 2,4-diaminobutyric acid and 2-amino-6N-oxalylureidopropionic acid (oxalylalbizziine) in seeds of acacia angustissima

A new amino acid previously detected in 17 species of Acacia has been isolated from seeds of Acacia angustissima and identified as oxalylalbizziine. These seeds also contain more than 6% dry weight of 2-amino-4-acetylaminobutyric acid, which has not been reported previously in a legume, and lower concentrations of 2,4-diaminobutyric acid.     

An improved synthesis of (2S, 4S)‐ and (2S, 4R)‐2‐amino‐4‐methyldecanoic acids: assignment of the stereochemistry of culicinins

An improved synthesis of (2S, 4S)‐ and (2S, 4R)‐2‐amino‐4‐methyldecanoic acids was accomplished using a glutamate derivative as starting material and Evans' asymmetric alkylation as the decisive step. The NMR data of the two diastereomers were measured and compared with those of the natural product. As a result, the stereochemistry of this novel amino acid unit in culicinins was assigned as (2S, 4R). Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.     

Production of (R)-2-(4-hydroxyphenoxy) propionic acid by Beauveria bassiana ZJB16007 in solid state fermentation using rice bran

Abstract

R-2-(4-hydroxyphenoxy)propionic acid (R-HPPA) is a key chiral intermediate for phenoxypropionic acid herbicide synthesis. In this study, to improve the production of R-HPPA with B. bassiana ZJB16007, the cultivation conditions in solid-state fermentation (SSF) were investigated. The effects of various substrates on R-HPPA production were evaluated and the process parameters were also optimized. The results showed that rice bran was the optimal substrate for R-HPPA production. The optimal medium components and cultivation conditions were: rice bran: silkworm chrysalis powder = 5.25: 2.25 (g: g), nutrient salts solution 12?mL which contained 50?g/L R-PPA, pH 5.0, and cultivated at 28?°C for 11 days. Under the optimized conditions, the transformation of R-HPPA was significantly improved and the yield of R-HPPA reached 77.78%, which was 15.14% higher than that of the control (67.55%). Therefore, SSF may serve as an alternative for R-HPPA production by B. bassiana ZJB16007.     

Oxidation of 2-keto-4-thiomethylbutyric acid (KTBA) by iron-binding compounds produced by the wood-decaying fungus Gloeophyllum trabeum

Abstract The ability of iron-binding compounds isolated from the brown-rot fungus Gloeophyllum trabeum to carry out one-electron oxidation reactions was established using a model substrate, 2- keto -4-thiomethylbutyric acid (KTBA). The oxidation reaction was monitored by measuring the amount of ethylene produced from the substrate by gas chromatography. The extent of the reaction was found to be influenced by the concentration of the chelators, and by iron and manganese.     

Kinetic resolution of 1-chloro-3-(1-naphthyloxy)-2-propanol,an intermediate in the synthesis of beta-adrenergic receptor blockers

(R)- and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol are intermediates in the synthesis of β-adrenergic blocking agents and antihypertensive drugs such as propranolol and nadoxolol. Herein, improvement in the preparation of racemic 1-chloro-3-(1-naphthyloxy)-2-propanol generated from 1-naphthol and epichlorohydrin are reported. In addition, kinetic resolution studies have been conducted to obtain both (R) and (S)-1-chloro-3-(1-naphthyloxy)-2-propanol. These compounds were obtained in highly optically pure form by the stereoselective hydrolysis of its acyl derivatives using whole cell preparations containing enzymes from native sources. The results were compared with those obtained using commercial lipases.     

Lipid‐dependent cytotoxicity by the lipase PLRP2 and by PLRP2‐positive cytotoxic T lymphocytes (CTLs)

IL‐4 induces a lipase, pancreatic lipase related protein 2 (PLRP2), in cytotoxic T lymphocytes (CTLs). Because PLRP2 in semen can mediate lipid‐dependent toxicity to sperm, we questioned whether CTL‐derived PLRP2 could support similar cytotoxicity toward tumor cells. Recombinant PLRP2 was toxic to P815 tumor cells in 48 h when lipid and another protein, colipase, were present. However, PLRP2‐positive CTLs (induced with many lots of IL‐4) were unable to mediate lipid‐dependent cytotoxicity. Notably, CTLs induced with only one lot of IL‐4 had lipid‐dependent cytotoxicity. The exceptional lot of IL‐4 was effective in multiple experiments at inducing lipid‐dependent cytotoxicity. The lipid‐dependent cytotoxicity it induced was determined to be perforin‐independent. CTLs induced with IL‐4 that was unable to induce lipid‐dependent cytotoxicity had mRNA for PLRP2 but not mRNA for colipase. Therefore, we added exogenous colipase to the CTL assays but still cytotoxicity was unchanged. We conclude (1) that lipid‐dependent cytotoxicity, promoted by the lipase PLRP2 and colipase, will kill tumor cells and (2) that more than PLRP2 alone is required for lipid‐dependent cytotoxicity mediated by CTLs. Copyright © 2009 John Wiley & Sons, Ltd.     

3-[2-Amino-2-imidazolin-4(5)-yl]alanine (enduracididine) and 2-[2-amino-2-imidazolin-4(5)-yl] acetic acid in seeds of Lonchocarpus sericeus

3-[2-Amino-2-imidazolin-4(5)-yl]alanine (enduracididine) and 2-[2-amino-2-imidazolin-4(5)-yl] acetic acid have been isolated from seeds of Lonchocarpus sericeus. The concentration of each compound was ca 0.5 % of the fresh seed weight.     

Isolation of (2S,4R)-2-amino-4-methyl-hex-5-enoic acid,a nonprotein amino acid,as an allelochemical from the fruiting bodies of Boletus fraternus Peck.

The mushroom Boletus fraternus Peck. shows allelopathy and suppresses the growth of broad leaf plants in nature. According to a bioassay-guided fractionation of the fruiting body of the fungus, a rare nonprotein amino acid was isolated as a major allelochemical. The chemical structure of the compound was determined to be (2S,4R)-2-amino-4-methyl-hex-5-enoic acid (5-dehydrohomoleucine) by analysis of ¹H- and ¹³C-nuclear magnetic resonance spectra and comparison with data from the literature. The allelochemical caused 50% inhibition of lettuce seedling radicle growth at a concentration of 34 ppm (w/v). Further, since radicle growth was directed away from the filter paper to prevent contact with the allelochemical at concentrations higher than 300 ppm (w/v), the fungus may use the allelochemical to protect its immediate environment from contamination by other plants.     

Temporary Changes in the dc ElectricalConductivity of MX (3-Chloro-4(Dichloromethyl)-5-Hydroxy-2(5H)-Furanone) Treated Collagen

The influence of MX(3-Chloro-4(Dichloromethyl)-5-Hydroxy-2(5H)- Furanone), a stronglymutagenic compound, on the temperature dependence of the dcelectrical conductivity of collagen as a function of time was studied.Collagen was immersed in MX solution, next dried and pressed intotablets. The MX concentration was measured by HPLC analysis.The reduction of MX concentration to 10% of the initial value wasobserved in the presence of collagen in the solution, whereas in thecontrol solution concentration of MX decreased to 70% of the initialvalue. Measurements of electrical conductivity were performed for thetemperature range 295–453K and activation energies for the chargeconduction process were calculated. Within the temperature range295–340K, the presence of MX decreased electrical conductivity ofcollagen. Calculated activation energies were typical for dry proteins.Within the temperature range 295–320K activation energy decreasedwith time, probably due to the stronger interactions in thecollagen-water-MX system. For temperatures between 320–410 and430–450K the activation energy was not time dependent and theapplication of MX did not change the structure of the collagenmacromolecule. The temporary changes occurring at the lowertemperatures being due solely to changes in the collagen-waterinteractions.     

响应面法优化酶法转化合成维生素C糖苷（AA-2G）条件的研究

采用Design—Expert软件的Central Composite Design（CCD）响应面设计对环糊精葡萄糖苷转移酶转化合成糖基抗坏血酸（AA-2G）的五个主要因素（转化时间、转化温度、pH、Vc浓度、β-环糊精浓度）进行了研究。采用降维分析方法对pH与转化时间、转化温度、Vc浓度、β-环糊精浓度以及反应温度与反应时间的交互作用对酶法转化合成AA-2G的影响进行了分析。建立了影响因素与响应值之间的回归方程,根据回归方程优化得到最佳转化条件为：转化时间25h,温度36．5℃,pH5．4,Vc72dL,β-环糊精55g／L。在此条件下,AA-2G的理论产量为10．06g／L,在验证实验中AA-2G的产量为9．76g／L,与预测的理论产量接近,比优化前提高了33％。