Biotransformation of β-hydroxyphenyl selenides, diphenyldiselenide and benzeneseleninic acid by whole cells of Aspergillus terreus

Aspergillus terreus CCT 3320 and A. terreus URM 3571 catalysed the biotransformations of organic β-hydroxyphenyl selenides through oxidation and methylation reactions. The kinetic resolution of (RS)-1-(phenylseleno)-2-propanol (1) via enantioselective oxidation produced (+)-(S)-1 in high enantiomeric excess (>99%) and in a yield of 50% as determined by product isolation. Oxidation of the R-enantiomer of 1, followed by elimination of the propyl moiety and subsequent methylation of the presumed intermediate, led to the formation of methylphenyl-selenide, which was isolated in a yield of 40%. Whole cells of A. terreus also biocatalysed transformations of diphenyldiselenide, benzeneseleninic acid, (RS)-1-(phenylseleno)-2-pentanol and (RS)-1-(phenylseleno)-3-methyl-2-butanol, but not of (RS)-1-(phenylseleno)-2-phenyl-methanol. This is the first report of the biomethylation of organoselenium compounds by whole cells of A. terreus.     

Asymmetric synthesis of arylselenoalcohols by means of the reduction of organoseleno acetophenones by whole fungal cells

A series of novel organoseleno acetophenones (3a–f) have been synthesized. The microbial reduction of the seleno ketones (3) has been evaluated using whole cells of Rhizopus oryzae CCT 4964, Aspergillus terreus CCT 3320, A. terreus CCT 4083 and Emericella nidulans CCT 3119. These microorganisms showed Prelog and anti-Prelog stereoselectivity, leading to the arylselenoalcohols in moderate to high enantiomeric excesses. The organoselenium compounds were compatible with the biocatalytic conditions employed.     

Characterization of two extracellular proteinases from Aspergillus terreus and their role in the formation of low molecular weight endoglucanases

Two extracellular proteolytic activities from the wood degrading fungus Aspergillus terreus have been characterized. Proteinase I (serine thiol-dependent enzyme) was active over a broad pH range (7·0–10·0) and at 55°C. The second proteinase (metalloproteinase) showed optimal activity at pH 6·0–7·0 and at 65–70°C. Both proteins had isoelectric points at acid pH and contained carbohydrate moieties. The metalloproteinase possessed a uniquely high content of serine and threonine and an extremely low percentage of glutamate and aspartate. The metalloproteinase was involved in the formation of the low molecular mass endoglucanases of A. terreus.     

Biotransformations of ortho-, meta- and para-aromatic nitrocompounds by strains of Aspergillus terreus: Reduction of ketones and deracemization of alcohols

Seven strains of the fungus Aspergillus terreus isolated from several provenances in Brazil, catalyzed biotransformations of ortho-, meta- and para-nitrophenyl compounds at different pH values. ortho-Nitroacetophenone and meta-nitroacetophenone were transformed into (S)-(+)-1-(ortho-nitrophenyl)ethanol and (S)-(−)-1-(meta-nitrophenyl)ethanol with high enantiomeric excess (e.e. ≥98%) and conversion (≥98%) by all the strains used. Deracemization of (RS)-1-(meta-nitrophenyl)ethanol was obtained with high selectivity (e.e. up to ≥98%) and good conversion (c 98%). The biotransformations in acidic medium using these fungus strains were more efficient than under basic or neutral conditions.     

Chemotaxonomy of Gentianopsis: Xanthones, C-glycosylflavonoids and carbohydrates

In the genus Gentiana s.l. (Gentianaceae), the status of the section Crossopetalum Froel, is still very much debated. On Morphological grounds. Ma regarded this section as an independent genus which he called Gentianopsis. In this paper we discuss this proposal, taking into account chemotaxonomic data (xanthones, carbohydrates and C-glycosylflavones) arising from an examination of leaves and flowers of 13 species including the type-species Gentianopsis barbata. Isoscoparin, primeverose. 1,3,7- and 1,3,7,8-O-substituted xanthones were present in all species, while 1,3,5,8-O-substituted xanthones were absent. These criteria clearly differentiate the group from Gentianella (occurrence of 1,3,5,8-O-substituted xanthones, absence of 1,3,7-O-substituted xanthones, presence of swertisin, absence of primeverosel in which they were previously included. Furthermore, a comparison of Crossopetalum with two species belonging to Gentiana s.s. (the type G. lutea L. and G. orbicularis Schur.) discloses some analogy with respect to xanthone composition (only 1,3,7- or 1,3,7,8-substitution, respectively). However, the presence of gentianoise in Gentiana s.s., in contrast to its absence in Gentianopsis, indicates that the latter should be excluded from Gentiana. The assessment on morphological grounds of the validity of the genus Gentianopsis Ma is thus reinforced. The evolutionary signification of the chemical characters and the phyletic relationships of Gentianopsis with the other genera of the Gentianinae are discussed.     

Uronic acid-containing glycopeptides from Fusarium oxysporum: Possible significance as chemotypes

Hot aqueous extraction of mycelia of Fusarium oxysporum, followed by fractionation on an anionic resin column gave glycopeptides FL-2 and FL-3. Methylation analysis and 1D and 2D NMR data demonstrated β-d-Manp units and partial hydrolysis gave -d-GlcpA(1→2)-d-Gal, arising from β-d-Galf-containing groups. Both are chemotaxonomic markers of Fusarium spp. FL-3 contained 2,6-di-O-substituted Manp, as well as 2,6-di-O-substituted Galf units, raising the possibility that the former are main-chain constituents, as well as the expected latter structure. The carbohydrate structures of FL-2 and FL-3 differ from those of previously examined polysaccharides of Fusarium spp., which are in turn all different from each other, so that they can serve as fingerprints. Possible variations in their main-chain structures can occur as well as those of their side-chains.     

Enzymatic evaluation of different Aspergillus strains by biotransformation of cyclic ketones

The potential of different Aspergillus strains in carrying out the biotransformation of cyclic ketones was investigated. All the strains employed showed alcohol dehydrogenase and Baeyer–Villiger monooxygenase activities. trans-2-Methylcyclohexanol and trans-4-methylcyclohexanol were prepared in a single isomeric form by the use of Aspergillus terreus SSP 1498 and the corresponding ketones. Baeyer–Villiger oxidation of cyclic ketones by all the fungi Aspergillus led to chiral lactones in good enantioselectivity.     

粗山羊草CCT家族基因序列分析及激素响应

开花是植物生长发育的重要过程。CCT家族基因在植物中广泛存在, 参与植物花期的调控过程。该文从粗山羊草(Aegilops tauschii)全基因组中分离出26个CCT基因, 它们分布于7对染色体上, 按照排列顺序将其命名为AetCCT1-26。AetCCT蛋白分子量介于14.9 kDa (AetCCT3)-83.2 kDa (AetCCT12)之间, 其中有25个蛋白包含完整的CCT保守结构域。系统发育分析显示, 12对粗山羊草/乌拉尔图小麦(Triticum urartu) CCT蛋白和9对粗山羊草/水稻(Oryza sativa) CCT蛋白为直系同源蛋白。通过公共数据的数字表达分析表明, AetCCT具有组织特异性和组成型2种表达形式, 其中AetCCT3、AetCCT4、AetCCT7及AetCCT9等9个基因在大部分组织中都有表达, 而AetCCT15、AetCCT21和AetCCT25等基因分别在种子、叶和根等少数组织中特异表达。AetCCT家族可以响应不同外源激素, 施用激素24小时和72小时后各成员对激素响应整体表现一致, 但不同成员对于不同激素的响应存在差异, 表明该家族成员在功能和行使方式等方面具有一定的多样性, 可能参与不同生长发育过程。光照条件影响AetCCT的表达, 说明光照和春化作用是影响与调控该家族基因表达的重要因素。研究结果有助于探索小麦(T. aestivum)进化、驯化和演变的规律, 以及认识重要农艺性状的形成与互作网络。     

Biohydroxylation of N,N-dialkylarylamines by the isolated topsoil bacterium Bacillus megaterium

Topsoil microorganisms were screened for their acceptability of the standard substrate N,N-dimethylaniline in bacterial ‘whole-cell’ incubations. One bacterium converted N,N-dimethylaniline and was identified as Bacillus megaterium by 16S rDNA analysis and DNA/DNA-hybridization. In contrast to the well-known C-hydroxylation by liver microsomes, leading to p-hydroxylation, B. megaterium formed o- and p-monohydroxylated products, i.e. N,N-dimethyl-2-aminophenol and N,N-dimethyl-4-aminophenol, both identified by gas chromatography–mass spectrometry (GC–MS) using synthesized reference compounds. The observed hydroxylation showed slight regioselectivity in favour of the o-hydroxylated product. Two further substrates, N,N-diethylaniline and N-ethyl-N-methylaniline, were also successfully biohydroxylated by B. megaterium with corresponding regioselectivity. Interestingly, aniline, known to be transformed easily by cytochrome P-450meg into p-aminophenol, was not accepted as substrate.     

Oxidation of both termini of p- and m-xylene by Escherichia coli transformed with xylene monooxygenase gene

Xylene monooxygenase (XMO) from Pseudomonas putida mt-2 catalyzes oxidation of methyl group of toluene and xylenes. While it has been postulated that this enzyme oxidizes one methyl group of xylene, we observed that both methyl groups in p- and m-xylene were oxidized to alcohol and aldehyde when the relevant genes (xylM and xylA) were co-expressed in Escherichia coli C600 and MC4100. When p-xylene was used as a substrate, p-hydroxymethylbenzaldehyde and p-xylyleneglycol were identified, in addition to p-methylbenzylalcohol and p-tolualdehyde. When m-xylene was used as a substrate, m-hydroxymethylbenzaldehyde and m-xylyleneglycol were identified, in addition to m-methylbenzylalcohol and m-tolualdehyde. Ratio of the products varied significantly according to the reaction condition and host strain, presumably reflecting the relative activity of XMO and host-derived dehydrogenase(s). Using various oxidized compounds as substrates, it was indicated that dialcohol (p- or m-xylyleneglycol) was formed via p- or m-hydroxymethylbenzaldehyde, respectively, rather than directly from corresponding monoalcohol (p- or m-methybenzylalcohol).     

Aromatic compounds from Delphinium venulosum

From the non-alkaloidal fractions of Delphinium venulosum, four known aromatic compounds cis and trans p-coumaric acids, p-hydroxybenzoic acid, protocatechuic acid methyl ester and a new aromatic compound 2,5,6-trihydroxypiperonylic acid methyl ester were isolated together with kaempferol, sitosterol and sitosteryl 3-glucoside. The structures of the compounds were established by spectral data.     

Two phenylpropanoids from Todaroa aurea subsp. Suaveolens

Two new phenylpropanoids, p-methoxytodadiol and suavediol were isolated from the aerial part and roots of Todaroa aurea subsp. suaveolens, together with the acetylenic compound, falcarinol.     

Purification and properties of lipase from a Bacillus strain for catalytic resolution of (R)-Naproxen

A Bacillus strain was screened for asymmetric resolution of (R)-Naproxen. The optical purity (ee (%)) of (R)-Naproxen was found to be 86.47% and conversion rate was 40–50% in bacterial cells PBS reaction system. The dissolved lipase was clarified from the Bacillus bacterial cells by centrifugation and loaded on a phenyl-Sepharose CL-4B column. After purification by a single hydrophobic chromatography, the activity of lipase was approximately 43 times higher than the crude one. The hydrolytic activity of lipase using Naproxen ethyl ester and p-nitrophenyl acetate (p-NPA) as substrate remained essentially constant during the purification procedure. A Bacillus strain with stereochemical selectivity was obtained.     

Pustulan and branched β-galactofuranan from the phytopathogenic fungus Guignardia citricarpa, excreted from media containing glucose and sucrose

Guignardia citricarpa is a phytopathogenic fungus and the causal agent of citrus black spot. Incubation in a semi-defined media resulted in formation of exopolysaccharides [EPS(s)]. A medium containing glucose gave rise to a (1→6)-linked β-glucan (200 kD), pustulan, which was characterized by NMR and methylation analysis. A sucrose-containing medium provided a homogalactan (376 kD) and methylation analysis showed nonreducing end- (20%), 6-O- (53%) and 5,6-di-O-substituted Galf units (27%). An HMQC spectrum of the homogalactan showed C-1/H-1 signals at δ 108.2/4.820, 108.3/4.820 and 107.1/5.079, corresponding to three types of β- -Galf units. A DEPT analysis showed inverted signals (CH₂) at δ 67.8 and 67.2, corresponding to 6-O-substituted β- -Galf units, whereas a C-5 signal at δ 77.0 suggests 5-O-substitution, confirming a novel structure for a β-galactofuranan.     

Bioreduction of 2-azido-1-arylethanones mediated by Geotrichum candidum and Rhodotorula glutinis

Enantioselective reductions of p-X-C₆H₄C(O)CH₂N₃ (X = H, Cl, Br, CH₃, OCH₃) mediated by Rhodotorula glutinis and Geotrichum candidum afforded the corresponding alcohols with complementary R and S configurations, respectively, in excellent yield and enantiomeric excesses. The obtained (R)-azidoalcohols are important starting materials for preparation of natural products and valuable pharmaceutical compounds such as (R)-Tembamide and (R)-Aegeline.     

Global analysis of CCT family knockout mutants identifies four genes involved in regulating heading date in rice

Many genes encoding CCT domain‐containing proteins regulate flowering time. In rice (Oryza sativa), 41 such genes have been identified, but only a few have been shown to regulate heading date. Here, to test whether and how additional CCT family genes regulate heading date in rice, we classified these genes into five groups based on their diurnal expression patterns. The expression patterns of genes in the same subfamily or in close phylogenetic clades tended to be similar. We generated knockout mutants of the entire gene family via CRISPR/Cas9. The heading dates of knockout mutants of only 4 of 14 genes previously shown to regulate heading date were altered, pointing to functional redundancy of CCT family genes in regulating this trait. Analysis of mutants of four other genes showed that OsCCT22, OsCCT38, and OsCCT41 suppress heading under long‐day conditions and promote heading under short‐day conditions. OsCCT03 promotes heading under both conditions and upregulates the expression of Hd1 and Ehd1, a phenomenon not previously reported for other such genes. To date, at least 18 CCT domain‐containing genes involved in regulating heading have been identified, providing diverse, flexible gene combinations for generating rice varieties with a given heading date.     

Nitrile biotransformation by Aspergillus niger

A nitrile-converting enzyme activity was induced in Aspergillus niger K10 by 3-cyanopyridine. The whole cell biocatalyst was active at pH 3–11 and hydrolyzed the cyano group into acid and/or amide functions in benzonitrile as well as in its meta- and para-substituted derivatives, cyanopyridines, 2-phenylacetonitrile and thiophen-2-acetonitrile. Amides constituted a significant part of the total biotransformation products of 2- and 4-cyanopyridine, 4-chlorobenzonitrile, 4-tolunitrile and 1,4-dicyanobenzene, while -substituted acrylonitriles gave amides as the sole products.     

Cytochrome b of the Dictyostelium discoideum plasma membrane

Cytochrome b of the plasma membrane of Dictyostelium discoideum was investigated in purified plasma membranes and in solubilized form. The membrane-bound cytochrome b can be reduced by NADH. This reduction is inhibited by p-hydroxymercuribenzoate. The reduced cytochrome b does not react with carbon monoxide. Its apparent molecular weight lies between 13000 and 16000. Tryptic digestion yields a large, heme-containing peptide with an apparent molecular weight between 12000 and 15000. After solubilization with cholate, cytochrome b can be enriched by reversed-phase HPLC, indicating that it contains also a hydrophobic component. With these properties, cytochrome b of the D. discoideum plasma membrane resembles microsomal cytochrome b₅.     

Synthesis of symmetric and unsymmetric 1,4-bis(p-R-phenylethynyl)benzenes via palladium/copper catalyzed cross-coupling and comments on the coupling of aryl halides with terminal alkynes

A series of symmetric 1, 4-bis(p-R-phenylethynyl)benzenes (6a-h) have been prepared via Pd¹¹/Cu¹ catalyzed cross- coupling of 1, 4-diiodobenzene (5) and p-substituted phenylethynes (4a-h). Similarly, the unsymmetric analogues (9a-c) were obtained from 1-iodo-4-(p-nitrophenylethynyl)benzene (8) and p-substituted phenylethynes (4c, 4d, 4g). Quantitative analysis of 1,4-(trimethylsilyl)butadiyne (10), produced in the catalytic coupling of ethynyltri- methylsilane with aryl halides using PdCl₂(PPh₃)₂/CuI in an amine solvent, confirmed that catalyst initiation proceeds via reduction of Pd¹¹ to Pd⁰ with concomitant oxidative homo-coupling of two ethynyltrimethylsilane molecules producing exactly one equivalent of 10 based on Pd¹¹. If air is present, the PdCl₂(PPh₃)₂/CuI/amine mixture provides a very effective system for catalytic oxidative homo-coupling of terminal alkynes to diynes and thus air must be rigorously excluded from the cross-coupling reactions. Hydrodehalogenation can compete effectively with the cross-coupling reaction for highly fluorinated aryl halides. Under certain conditions, the fluorinated aryl bromide or iodide can serve as the oxidant for the alkyne to diyne oxidative homo-coupling reaction. This can be avoided by appropriate choice of reaction conditions and reagents. These competing pathways have significant implications for the cross-coupling of aryl halides with terminal alkynes and are discussed herein.     

Effect of CO2 on carbonic anhydrase in Avena sativa and Zea mays

In leaves of Zea mays kept in air with reduced or increased CO₂, the level of carbonic anhydrase is reduced or increased respectively. In Avena sativa an opposite effect of pCO₂ is observed. In both cases the enzyme activity rapidly reached normal values when the plants were transferred back to normal atmosphere.