Identification of Poly-<Emphasis Type="Italic">N</Emphasis>-Acetyllactosamine-Carrying Glycoproteins from HL-60 Human Promyelocytic Leukemia Cells Using a Site-Specific Glycome Analysis Method,Glyco-RIDGE

To elucidate the relationship between the protein function and the diversity and heterogeneity of glycans conjugated to the protein, glycosylation sites, glycan variation, and glycan proportions at each site of the glycoprotein must be analyzed. Glycopeptide-based structural analysis technology using mass spectrometry has been developed; however, complicated analyses of complex spectra obtained by multistage fragmentation are necessary, and sensitivity and throughput of the analyses are low. Therefore, we developed a liquid chromatography/mass spectrometry (MS)-based glycopeptide analysis method to reveal the site-specific glycome (Glycan heterogeneity-based Relational IDentification of Glycopeptide signals on Elution profile, Glyco-RIDGE). This method used accurate masses and retention times of glycopeptides, without requiring MS2, and could be applied to complex mixtures. To increase the number of identified peptide, fractionation of sample glycopeptides for reduction of sample complexity is required. Therefore, in this study, glycopeptides were fractionated into four fractions by hydrophilic interaction chromatography, and each fraction was analyzed using the Glyco-RIDGE method. As a result, many glycopeptides having long glycans were enriched in the highest hydrophilic fraction. Based on the monosaccharide composition, these glycans were thought to be poly-N-acetyllactosamine (polylactosamine [pLN]), and 31 pLN-carrier proteins were identified in HL-60 cells. Gene ontology enrichment analysis revealed that pLN carriers included many molecules related to signal transduction, receptors, and cell adhesion. Thus, these findings provided important insights into the analysis of the glycoproteome using our novel Glyco-RIDGE method.

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Fabrication of mesoporous Pt nanotubes utilizing dual templates under a reduced pressure condition

Pt nanotubes with mesoporous walls have been successfully prepared for the first time by the combination of hard templates (porous anodic alumina membranes, PAAM) and soft templates (lyotropic liquid crystals, LLC).     

Synthesis, X-ray crystallographic analysis, and theoretical structure analysis of tetrathienylethenes designed for photo- and electrochromism

As part of an effort to develop a new chromic system that responds to both photoexcitation and electron transfer, tetrakis(2-methylthien-3-yl)ethene (3a) and its tetrakismethylthio derivative (3b) were synthesized. The results of X-ray crystallographic and theoretical analyses of these substances suggest that (1) conformers of 3 with an antiparallel arrangement of two vicinal thienyl groups will undergo photocyclization, and (2) the most stable conformer of 3 having an anti-double parallel conformation will not. These predictions were preliminarily confirmed by the results of photochemical and cyclic voltammetry studies.     

Copper-catalyzed anti-hydrophosphination reaction of 1-alkynylphosphines with diphenylphosphine providing (Z)-1,2-diphosphino-1-alkenes

Hydrophosphination of 1-alkynylphosphines with diphenylphosphine proceeds in an anti fashion under copper catalysis, providing an easy and efficient access to a variety of (Z)-1,2-diphosphino-1-alkenes and their sulfides. The reaction is highly chemoselective and can be performed even in an aqueous medium. The reaction is reliable enough to realize a gram-scale synthesis of (Z)-1,2-diphosphino-1-alkene. Radical reduction of the diphosphine disulfides with tris(trimethylsilyl)silane yields the parent trivalent diphosphines without suffering from the isomerization of the olefinic geometry. Enantioselective hydrogenation of (Z)-3,3-dimethyl-1,2-bis(diphenylthiophosphinyl)-1-butene followed by desulfidation leads to a new chiral bidentate phosphine ligand.     

Quinoline-based tetradendate nitrogen ligands stabilize the bis(micro-oxo) dinuclear manganese(iii,iii) core

Quinoline-based, tetradentate nitrogen ligands, N,N'-bis(2-quinolylmethyl)-N,N'-dialkyl-1,2-ethanediamine (alkyl = methyl, bqdmen; ethyl, bqdeen; isopropyl, bqdpen), have been investigated as the supporting ligands for the formation of bis(micro-oxo) dinuclear manganese complexes. Bis(micro-oxo)Mn(2)(iii,iii) complexes and were obtained for bqdmen and bqdeen, respectively, as evidenced by X-ray crystallography, whereas bqdpen did not afford any manganese complexes due to its steric bulk. Complexes and exhibit highly positive Mn(2)(iii,iii)/Mn(2)(iii,iv) and Mn(2)(iii,iv)/Mn(2)(iv,iv) redox couples relative to the corresponding pyridine-ligated (micro-O)(2)Mn(2)(iii,iii) complexes.     

High-performance thin-layer chromatography/mass spectrometry for rapid analysis of neutral glycosphingolipids

Direct coupling of high-performance thin-layer chromatography (HPTLC) to matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometry (MS) was shown to be a reliable and reproducible method to obtain structural information and fundamental properties of glycosphingolipids (GSLs). We report a protocol for the preparation of neutral GSL extracts from mouse tissues and demonstrate the applicability of HPTLC/MS to these preparations. The protocol consists of lipid extraction and ion exchange chromatography followed by a mild alkaline treatment and a reversed-phase cartridge extraction. Possible structures for each GSL are proposed based on HPTLC/MS analyses. This fast and simple method can be used to screen neutral GSL extracts obtained from tissues and cells without isolation and purification into individual GSLs.     

Cu(I)-assisted carbon---carbon bond forming reactions of γ,γ-dialkoxyallylic zirconium species: a new versatile homoenolate equivalent of propionate

In the presence of CuCN, reaction of γ,γ-dialkoxyallylic zirconium species 1 with acyl chloride or allylic phosphates proceeded at the -position of 1 to give alkanoates 3 after aqueous work-up. The ketene dialkylacetal moiety in the coupling products 2 can be used for further bond forming reaction with electrophiles such as nitrosobenzene, nitrostyrene or trichloroacetylisocyanate.     

Total Synthesis of 6-Deoxydihydrokalafungin,a Key Biosynthetic Precursor of Actinorhodin,and Its Epimer

In this article, we report the total synthesis of 6-deoxydihydrokalafungin (DDHK), a key biosynthetic intermediate of a dimeric benzoisochromanequinone antibiotic, actinorhodin (ACT), and its epimer, epi-DDHK. Tricyclic hemiacetal with 3-siloxyethyl group was subjected to Et₃SiH reduction to establish the 1,3-cis stereochemistry in the benzoisochromane, and a subsequent oxidation/deprotection sequence then afforded epi-DDHK. A bicyclic acetal was subjected to AlH₃ reduction to deliver the desired 1,3-trans isomer in an approximately 3:1 ratio, which was subjected to a similar sequence to that used for the 1,3-cis isomer that successfully afforded DDHK. A semisynthetic approach from (S)-DNPA, an isolable biosynthetic precursor of ACT, was also examined to afford DDHK and its epimer, which are identical to the synthetic products.     

Viscoelastic properties of poly(methyl methacrylate) with high glass transition temperature by lithium salt addition

The effect of ion‐dipole interaction between lithium cations and oxygen atoms in poly(methyl methacrylate) (PMMA), which leads to the great enhancement of glass transition temperature (T_g), on the linear viscoelastic properties is studied using binary blends of PMMA and lithium trifluoromethanesulfonate (LiCF₃SO₃). The strong interaction at low temperature leads to the high modulus in the glassy region even near T_g. The interaction becomes weak as increasing the temperature. Consequently, the rheological terminal region is clearly detected without a marked enhancement of steady‐state compliance, although the zero‐shear viscosity increases by the LiCF₃SO₃ addition. The result indicates that the crosslinking due to the ion‐dipole interaction has a lifetime that decides the longest relaxation time. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2388–2394     

Stelliferins J-N, isomalabaricane-type triterpenoids from Okinawan marine sponge Rhabdastrella cf. globostellata

Five new isomalabaricane-type triterpenoids, stelliferins J-N (1-5), were isolated from Okinawan marine sponge Rhabdastrella cf. globostellata. The structures of 1-5 were elucidated from the spectroscopic data and chemical means including application of a modified Mosher’s method and an exciton chirality method.