The transient and steady-state response of a hereditary system

The distinctive features of the response of a system with limited slip and trigonometric excitation are discussed. Both the steady-state and transient behavior of this hereditary system are predicted using a first order approximation technique, and the predictions are compared with the results of “exact” numerical solutions.     

Glycoinsulins: dendritic sialyloligosaccharide-displaying insulins showing a prolonged blood-sugar-lowering activity

Mono-, di-, and trisialyloligosaccharides were introduced to mutant insulins through enzymatic reactions. Sugar chains were sialylated by alpha2,6-sialyltransferase (alpha2,6-SiaT) via an accessible glutamine residue at the N-terminus of the B-chain attached by transglutaminase (TGase). Sia2,6-di-LacNAc-Ins(B-F1Q) and Sia2,6-tri-LacNAc-Ins(B-F1Q), displaying two and three sialyl-N-acetyllactosamines, respectively, were administered to hyperglycemic mice. Both branched glycoinsulins showed prolonged glucose-lowering effects compared to native or lactose-carrying insulins, showing that sialic acid is important in obtaining a prolonged effect. Sia2,6-tri-LacNAc-Ins(B-F1Q), in particular, induced a significant delay in the recovery of glucose levels.     

Stereoselective tris-glycosylation to introduce beta-(1-->3)-branches into gentiotetraose for the concise synthesis of phytoalexin-elicitor heptaglucoside

Dodecyl thioglycosides (3, 4, 5) were prepared by conventional transformation of d-glucose and used as new glycosyl donors for a short-step synthesis of phytoalexin elicitor heptaglucoside. A gentio-tetraoside derivative (6) having three hydroxyl groups was synthesized by NIS-TfOH promoted glycosylate in more than 90% yield followed by selective removal of temporary protective groups. Undesired formation of alpha-glycosides at the introduction of beta-(1-->3)-branches into gentio-oligosaccharides was found to be suppressed by use of a thiophilic reagent system, BSP (1-benzenesulfinyl piperidine)-Tf2O, giving the heptaglucoside in only four glycosylation steps.     

Preparation of Chitinous Compound/Gelatin Composite and Their Biological Application

Chitin, a natural abundant polysaccharide, have been investigated as prospected biochemical material due to its several biological advantages. It is insoluble in the most of the organic solvents due to its rigid crystalline structure. However, chitin regenerated hydrogel (RG) has been prepared by using the saturated calcium solvent system under mild conditions. And also, swelling hydrogel (SG) was prepared by using water. In this study, we prepared the suspension of chitinous hydrogel, and applied to fabricated the chitinous compound/gelatin composite sheets. Additionally, N-acetyl D-(+)-glucosamine was added into some composite sheets. We investigated the mechanical properties and growth of NIH/3T3 fibroblast cell for the prepared composite sheet.     

Synthesis of a tetrasaccharide repeating unit of O-antigenic polysaccharide of Salmonella enteritidis by use of unique and odorless dodecyl thioglycosyl donors

The first total synthesis of a unique tetrasaccharide repeating unit of lipopolysaccharide from Salmonella enteritidis has been accomplished by assembly of dodecyl thioglycosides. The crucial key steps were preparation of a rare branched dideoxy sugar, d-tyvelose (3,6-dideoxy-d-arabino-d-hexose) and sequential regioselective glycosylation at 2,3-positions of a central d-mannose residue 5 with d-tyvelose 6 and d-galactose donors 7.     

Preparation and characterization of gel electrolyte with bacterial cellulose coated with alternating layers of chitosan and alginate for electric double-layer capacitors

Research on Chemical Intermediates - A novel gel electrolyte has been prepared using bacterial cellulose (BC) coated with chitosan (CTS) and alginate (Alg) layers, which contain...     

Erythrocyte-like liposomes prepared by means of amphiphilic cyclodextrin sulfates

A novel class of sulfated glycolipids with excellent self-assembling capacity to form stable monolayers at an air-water interface and specific erythrocyte-like liposomes was synthesised from alpha, beta, and gamma-cyclodextrins as starting materials.     

Properties of the solutions of a class of dynamical hereditary systems

A general class of dynamical systems with hereditary behavior is formulated mathematically. Fundamental properties of the exact solutions to the corresponding initial value problem are presented as four theorems. Existence, uniqueness, and boundedness of solutions is examined.     

Chemical and enzymatic synthesis of glycocluster having seven sialyl lewis X arrays using β-cyclodextrin as a key scaffold material

An efficient and practical method for the large-scale synthesis of an anti-inflammatory glycocluster having seven sialyl Lewis X (SLeX) residues was established on the basis of chemical and enzymatic strategy from β-cyclodextrin (β-CD) as a key starting scaffold material. A key intermediate, β-CD derivative having seven N-acetyl-d-glucosamine (GlcNAc) residues [(GlcNAc)₇CD], was prepared by a coupling reaction with heptakis 6-deoxy-6-iodo-β-cyclodextrin and sodium thiolate containing a GlcNAc residue. Subsequent sugar elongation reactions of (GlcNAc)₇CD proceeded smoothly by means of β-1,4-galactosyltransferase, α-2,3-sialyltransferase, and α-1,3-fucosyltransferase V in the presence of the corresponding sugar nucleotides (UDP-Gal, CMP-Neu5Ac, and GDP-Fuc) and allowed to give a mono-dispersed glycodendrimer (M_w=7924.5, calcd for C₃₀₁H₄₉₀N₂₁O₁₉₆S₇Na₇; MALDI-TOF MS, m/z 7946 [M+Na]⁺) that completely substituted with seven SLeX branches at C-6 positions in excellent overall yield (74%, 3 steps). Hyper-branched glycodendrimer, (SLeX)₇CD, exhibited highly amplified inhibitory effect on the interaction of E-selectin with SLeXn-BSA immobilized on the sensor chip by means of surface plasmon resonance method.     

Dodecyl thioglycopyranoside sulfates: novel sugar-based surfactants for enantiomeric separations by micellar electrokinetic capillary chromatography

Four novel chiral anionic surfactants having carbohydrate hydrophilic heads, sodium n-dodecyl 1-thio-beta-D-glucopyranoside 6-hydrogen sulfate (6-betaGlcD), sodium n-dodecyl 1-thio-beta-L-glucopyranoside 6-hydrogen sulfate (6-betaGlcL), sodium n-dodecyl 1-thio-beta-L-fucopyranoside 3-hydrogen sulfate (3-betaFucL), and sodium n-dodecyl 1-thio-alpha-L-rhamnopyranoside 3-hydrogen sulfate (3-alphaRhaL), were synthesized by selective sulfation of the corresponding thioglycosides. Their CMC determined by fluorescence using pyrene as a probe in water was 1.3-2.7 mM. These surfactants found to be useful as chiral selectors for enantiomeric separation by MEKC. The enantiomeric separation was optimized with respect to pH, buffer concentration, and surfactant concentration. Under the optimized conditions (50 mM phosphate buffer at pH 6.5, 30 mM surfactant, 20 kV), the enantiomeric separations of five dansylated amino acids (Dns-AAs) were achieved within approximately 20 min with the migration order of Val相似文献