Suramin is a Novel Activator of PP5 and Biphasically Modulates S100-Activated PP5 Activity

Suramin is an activator of ryanodine receptors and competitively binds to the calmodulin-binding site. In addition, S100A1 and calmodulin compete for the same binding site on ryanodine receptors. We therefore studied the effects of suramin on protein phosphatase 5 (PP5) and S100-activated PP5. In the absence of S100 proteins, suramin bound to the tetratricopeptide repeat (TPR) domain of PP5 and activated the enzyme in a dose-dependent manner. In the presence of S100A2/Ca²⁺, lower concentrations of suramin dose-dependently inhibited PP5 activity as an S100 antagonist, whereas higher concentrations of suramin reactivated PP5. Although the C-terminal fragment of heat shock protein 90 (HspC90) also weakly activated PP5, the binding site of suramin and HspC90 may be different, and addition of suramin showed no clear effect on the phosphatase activity of PP5. Similar biphasic effects of suramin were observed with S100A1-, S100B- or S100P-activated PP5. However, the inhibitory effects of lower concentrations of suramin on S100A6-activated PP5 are weak and high concentrations of suramin further activated PP5. SPR and the cross-linking study showed inhibition of the interaction between S100 protein and PP5 by suramin. Our results revealed that suramin is a novel PP5 activator and modulates S100-activated PP5 activity by competitively binding to the TPR domain.     

Identification of the inclusion complexation between phenyl β-d-(13C6)glucopyranoside and α-cyclodextrin using 2D 1H or 13C DOSY spectrum

This study describes the 2D ¹H and ¹³C diffusion-ordered NMR spectroscopy (DOSY) experiments using the mixed sample of α-cyclodextrin (α-CyD) and phenyl β-d-(¹³C₆)glucopyranoside (1). Both the 2D ¹H and ¹³C DOSY spectra showed the component with a diffusion coefficient different from those of α-CyD and 1, which suggested the inclusion complexation of α-CyD with 1.     

Catalytic asymmetric hydroxylation of α-alkoxycarbonyl amides with a Pr(OPr)3/amide-based ligand catalyst

A catalytic asymmetric hydroxylation of N-nonsubstituted α-alkoxycarbonyl amides is described. A new effective catalyst comprising Pr(OⁱPr)₃ and a fluoro-substituted amide-based ligand was identified using oxaziridine as the oxidizing reagent. The catalyst components were in dynamic equilibrium in the reaction mixture, which assembled to form the associated transition state through metal coordination and hydrogen bonding.     

Experimental and numerical study of mechanism of glass modification process by continuous-wave laser backside irradiation (CW-LBI)

The modification of transparent materials using a femtosecond laser has been studied. We previously proposed a new method of modifying glass using a continuous-wave laser, named continuous-wave laser backside irradiation (CW-LBI), in which CW laser illumination induces a change in the refractive index without cracking the glass. In this study, we investigated the process of glass modification by CW-LBI using time-lapsed imaging and by calculation of the temperature. First, the modification of glass was observed by the shadowgraph method, and it was found that thermal radiation was included in the phenomena that occurred when the glass was modified. Second, the time-lapsed temperature distribution was calculated. The temperature distribution was roughly in accordance with the shape of the modified area observed in the shadowgraphs. We concluded that the radius of the modified area is dependent on the temperature reached in the glass.     

Complex Spherical Designs and Codes

Real spherical designs and real and complex projective designs have been shown by Delsarte, Goethals, and Seidel to give rise to association schemes when the strength of the design is high compared to its degree as a code. In contrast, designs on the complex unit sphere remain relatively uninvestigated, despite their importance in numerous applications. In this paper, we develop the notion of a complex spherical design and show how many such designs carry the structure of an association scheme. In contrast with the real spherical designs and the real and complex projective designs, these association schemes are nonsymmetric.     

Combinatorial Synthesis of Deoxyhexasaccharides Related to the Landomycin A Sugar Moiety,Based on an Orthogonal Deprotection Strategy

In this report, we describe the stereoselective synthesis of a combinatorial library comprised of 16 deoxyhexasaccharides that are related to a landomycin A sugar moiety, based on an orthogonal deprotection strategy. The use of an olivosyl donor containing a benzyl ether at the C3 position and benzoyl ester at the C4 position, and the olivosyl donor, a naphthylmethyl ether, and a p‐nitrobenzylethyl or benzyl sulfonyl ester enabled the synthesis of a set of four diolivosyl units containing a hydroxyl group at the C3 or C4 position by a simple glycosylation and deprotection procedure. Using a phenylthio 2,3,6‐trideoxyglycoside, α‐selective glycosidation proceeded without anomerization of the 2,6‐dideoxy‐β‐glycosides. In addition, alkylhydroquinone and levulinoyl groups were found to be an effective set of orthogonal protecting groups for the anomeric position and a hydroxyl group. The coupling of all combinations of trisaccharide units in a β‐selective manner was accomplished by activation of the glycosyl imidate with I₂ and Et₃SiH. No cleavage of the acid‐labile 2,3,6‐trideoxyglycoside was observed under the conditions used for the reactions. Finally, all of the protected hexasaccharides were deprotected by hydrolysis of the esters, microwave (MW) assisted cleavage of the 2‐trimethylsilylethoxymethoxy (SEM) ether, and a Birch reduction.     

An enantioselective approach to (−)-platencin via catalytic asymmetric intramolecular cyclopropanation

This Letter describes an enantioselective approach to (−)-platencin. A uniquely functionalized chiral intermediate, which was prepared via the highly enantioselective catalytic asymmetric intramolecular cyclopropanation (CAIMCP) that we have developed, was successfully transformed to Nicolaou’s intermediate in his total synthesis of (−)-platencin.