A cell factory of Bacillus subtilis engineered for the simple bioconversion of myo-inositol to scyllo-inositol, a potential therapeutic agent for Alzheimer's disease

<p>Abstract</p> <p>Background</p> <p>A stereoisomer of inositol, <it>scyllo</it>-inositol, is known as a promising therapeutic agent for Alzheimer's disease, since it prevents the accumulation of beta-amyloid deposits, a hallmark of the disease. However, this compound is relatively rare in nature, whereas another stereoisomer of inositol, <it>myo</it>-inositol, is abundantly available.</p> <p>Results</p> <p><it>Bacillus subtilis </it>possesses a unique inositol metabolism involving both stereoisomers. We manipulated the inositol metabolism in <it>B. subtilis </it>to permit the possible bioconversion from <it>myo</it>-inositol to <it>scyllo</it>-inositol. Within 48 h of cultivation, the engineered strain was able to convert almost half of 10 g/L <it>myo</it>-inositol to <it>scyllo</it>-inositol that accumulated in the culture medium.</p> <p>Conclusions</p> <p>The engineered <it>B. subtilis </it>serves as a prototype of cell factory enabling a novel and inexpensive supply of <it>scyllo</it>-inositol.</p

Helical Nanographenes Embedded with Contiguous Azulene Units

うねり構造をもつグラフェンナノリボンの精密合成に成功 --非ベンゼノイド構造の新規構築反応を開発--. 京都大学プレスリリース. 2020-07-20.The azulene moiety, composed of contiguous pentagonal and heptagonal rings, is a structural defect that alters the electronic, magnetic, and structural properties of graphenes and graphene nanoribbons. However, nanographenes embedded with an azulene cluster have not been widely investigated because these compounds are difficult to synthesize in their pure form. Herein, azulene-embedded nanographenes bearing a unique cove-type edge were synthesized by a novel synthetic protocol. Experimental and theoretical investigations revealed that this cove edge imparts stable helical chirality, unlike normal cove edges. The in-solution self-association behavior and the structural, electronic, and electrochemical properties were also described in detail

Site-selective benzoin-type cyclization of unsymmetrical dialdoses catalyzed by N-heterocyclic carbenes for divergent cyclitol synthesis

A highly site-selective N-heterocyclic carbene (NHC)-catalyzed benzoin-type cyclization of unsymmetrical dialdoses is developed to enable a divergent cyclitol synthesis. The choice of chiral NHCs and protecting groups affects the site-selectivity. The resulting inososes are converted into epi-, muco- and myo-inositol, and their chiral protected derivatives are formed in good yields

Optical resolution via catalytic generation of chiral auxiliary

A new catalytic method for separating enantiomers of racemic compounds is proposed. Catalytic asymmetric addition of chiral trans-2-substituted cyclohexanols to imines provided diastereomeric mixtures of aminals, and the subsequent separation of the enantiomers by silicagel column chromatography and the hydrolysis of the aminals produced the alcohols in an optically active form

Oxa- and Azacycle-formation via Migrative Cyclization of Sulfonylalkynol and Sulfonylalkynamide with NHeterocyclic Carbene

An N-heterocyclic carbene promotes cyclization of sulfonylalkynols and sulfonylalkynamides that accompanies 1,2-migration of the sulfonyl groups. This reaction provides a novel access to oxa- and azacycles possessing a pendent vinyl sulfone functionality, which in turn is amenable for further transformations

Striking Difference between Succinimidomethyl and Phthalimidomethyl Radicals in Conjugate Addition to Alkylidenemalonate Initiated by Dimethylzinc

We used dimethylzinc to develop a conjugate addition reaction of imidomethyl radicals to alkylidenemalonates using dimethylzinc, in which we observed a significant difference between succinimidomethyl and phthalimidomethyl radicals. This reaction provides new access to γ- aminobutyric acid derivatives, which often function as neurotransmitters

Desymmetrization of acid anhydride with asymmetric esterification catalyzed by chiral phosphoric acid

Asymmetric desymmetrization of σ-symmetric acid anhydrides was achieved with chiral phosphoric acid as a Brønsted acid catalyst. The key of success was finding of benzhydrol and 2,2-diphenylethanol as the nucleophiles of choice. The corresponding half esters were obtained in good yields with high selectivity

An automatic peak deconvolution code for Raman spectra of carbonaceous material and a revised geothermometer for intermediate- to moderately high-grade metamorphism

Carbonaceous material (CM) undergoes progressive changes that reflect its thermal history. These changes are in general irreversible and provide valuable information for understanding diagenetic and metamorphic processes of crustal rocks. Among various approaches to quantify these changes, the R2 ratio, area ratio of specific peaks in CM Raman spectra, is widely used to estimate the maximum temperature of intermediate- to moderately high-grade metamorphism. The calculation of the R2 ratio requires peak deconvolution of the original spectrum, and the results depend on the details of how this is carried out. However, a clear protocol for selecting appropriate initial conditions has not been established and obtaining a reliable temperature estimate depends at least in part on the experience and skill of the operator. In this study, we developed a Python code that automatically calculates the R2 ratio from CM Raman spectra. Our code produces R2 ratios that are generally in good agreement with those of Aoya et al. (J Metamorph Geol 28:895–914, 2010, https://doi.org/10.1111/j.1525-1314.2010.00896.x) for the same Raman data, with much less time and effort than was the case in the previous studies. We have confirmed that the code is also applicable to other previous datasets from both contact and regional metamorphic regions. The overall trend of the recalculated data indicates that samples with R2 greater than ~ 0.7 are not sensitive to the changes in CM maturity and thus should not be used for the calibration of an R2-based geothermometer. We propose a modified geothermometer for contact metamorphism that is strictly applicable to samples with R2 from 0.023 to 0.516, with the proviso that a laser with a wavelength of 532 nm should be used. A slight extrapolation of the newly proposed geothermometer up to R2 of 0.57 provides a temperature estimate that is consistent with the geothermometer of Kaneki and Kouketsu (Island Arc 31:e12467, 2022; https://doi.org/10.1111/iar.12467); the boundary between the two geothermometers corresponds to a temperature of 391 °C

3,6-Diphenyltetrazine as Cathode Active Material for Sodium Ion Batteries

3, 6-diphenyltetrazine (DPT) is an electron-deficient π-conjugated molecule with a perfectly planar structure and high crystallinity. In this study, discharge-charge tests of crystalline DPT as a cathode material for sodium ion batteries were conducted. DPT showed an initial reversible capacity of 102 mAh/g (theoretical capacity 114 mAh/g), corresponding to one electron reaction. The plateau of the discharge-charge profiles was observed at 1.9–2.1 V vs. Na/Na⁺. According to the ex-situ XRD, FT-IR, and XPS measurements to investigate the discharge-charge mechanism, the redox center was identified as the conjugated tetrazine ring. DPT was in a crystalline form in both the charged and discharged state and indicated the potential as a reversible Na ion host

Mechanistic Support for Intramolecular Migrative Cyclization of Propargyl Sulfones Provided by Catalytic Asymmetric Induction with a Chiral Counter Cation Strategy

We previously reported an intramolecular migrative cyclization of propargylsufones and sulfonylalkynamides giving oxa- and azacycles, respectively. To confirm the postulated reaction mechanism, the reaction was conducted with chiral nucleophiles such as N-heterocyclic carbenes, phosphines, and pyridines, or with sulfinate anions and chiral cations. As expected, migrative cyclization proceeded to give the enantiomerically enriched products. These results strongly support the postulated mechanism and provide the first example of the asymmetric version of this reaction