Preparation and Use of Polyurethane Enzyke Particles

The preparation and use of immobilized enzyme particles by disrersior and radiation polymerization technique in polyurethane prepolymer using polylene-2,4-diisocyanate, 2-hydroryethyl methacrylate, pentamethylene glycol, and cellulase are presented. The enzyme was added to form the particles (10–100C μm in diameter) under stirring of the mixture containing the prepolymer and enzyme solution, in which the enzyme was covalently bound to the surface of the particle. The size of the particles varied with the concentration of the enzyme and monomer. The enzymatic activity of the particles varied with the particle diameter, composition of monomer, and dispersion temperature.     

Synthetic Studies on Sialoglycoconjugates 14: Synthesis of Ganglioside GM3 Analogs Containing The Carbon 7 And 8 Sialic Acids

ABSTRACT

Ganglioside GM₃ analogs, containing 5-acetamido-3, 5-dideoxy-L-arabino-heptulosonic acid and 5-acetamido-3, 5-dideoxy-D-galacto-octulosonic acid have been synthesiyed. Glycosylation of 2-(trimethylsilyl)ethyl 0-(6-0-benzoyl-ß-D-galactopyranosyl)-(l→4)-2, 6-di-0-benzoyl-ß-D-glucopyranoside (5), with methyl (methyl 5-acetamido-4, 7-di-0-acetyl-3, 5-dideoxy-2-thio-ß-L-arabino-2-heptulo-pyranosid)onate (2) or with methyl (methyl 5-acetamido-4, 7, 8-tri-0-acetyl-3, 5-dideoxy-2-thio-α-D-galacto-2-octulopyranosid)onate (4), which were respectively prepared from the corresponding 2-S-acetyl derivatives (1 and 3) by selective 2-S-deacetylation and subsequent S-methylation, using dimethyl(methylthio)sulfonium triflate as a glycosyl promoter, gave 2-(trimethylsilyl)ethyl 0-(methyl 5-acet-amido-4, 7-di-0-acetyl-3, 5-dideoxy-ß-L-arabino-2-heptulopyranosyl-onate)-(2→3)-0-(6-0-benzoyl-ß-D-galactopyranosyl)-(1→4)-2, 6-di-0-benzoyl-ß-D-glucopyranoside (6) and 2-(trimethylsilyl)ethyl (0)-(methyl 5-acetamido-4, 7, 8-tri-0-acetyl-3, 5-dideoxy-α-D-galacto-2-octulopyranosylonate)-(2→3)-0-(6-0-benzoyl-ß-D-galactopyranosyl)-(l-4)-2, 6-di-0-benzoyl-ß-D-glucopyranoside (10), respectively. Compounds 6 and 10 were converted, via 0-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group, and subsequent imidate formation, into the corresponding trichloroacetimidates 9 and 13, respectively.

Glycosylation of (2S, 3R, 4E)-2-azido-3-0-benzoyl-4-octadecen1, 3-duik (14) with 9 or 13 affored the ß-glcosides (15 and 18), which were converted, via selective reduction of the azide group, coupling with octadecanoic acid, 0-deacylation, and deesterification, into the title compounds, respectively.     

Synthetic Studies on Sialoglycoconjugates 15: Synthesis of Ganglioside GM3 Analogs Containing A Variety Of Lipophilic Parts

ABSTRACT

Several ganglioside GM₃ analogs, containing a variety of lipophilic parts in place of the ceramide moiety have been synthesized. Glycosylation of (2S, 3R, 4E)-2-azido-3-0-benzoyl-4-octa-decen-l, 3-diol (2) with 0-(methyl 5-acetamido-4, 7, 8, 9-tetra-0-acetyl-3, 5-dideoxy-o-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-(2, 4-di-0-acetyl-6-0-benzoyl-ß-D-galactopyranosyl)-(l→4)-3-(1)-acetyl-2, 6-di-0-benzoyl-α-D-glucopyranosyl trichloroacetimidate (1) gave the 8-glycoside (5), which was converted, via selective reduction of the azide group, introduction of acyl groups, 0-deacylation, and de-esterification, into the desired compounds (10-12). On the other hand, coupling of 1 with 3-benzyloxycarbonyl-amino-1-propanol (3) or (2RS)-3-benzyloxycarbonylamino-2-0-benzoyl-1, 2-propanediol (4) gave the corresponding ß-glycosides 13 and 14, respectively. These were converted by N-debenzyloxycarbonylation, coupling with 2-tetradecylhexadecanoic acid, 0-deacylation, and hydrolysis of the methyl ester group, into the end products (17 and 18).     

Nonreducing-Sugar Subunit Analogs of Bacterial Lipid a Carrying the Ester-Bound (3R)-3-(Acyloxy)Tetradecanoyl Group

Abstract

In order to elucidate further the relationship between the composition of the fatty acyl groups in the nonreducing-sugar subunit of bacterial lipid A and its biological activity, 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-2-[(3R)-3-hydroxytetradecanamido]-4-O-phosphono-D-glucose [GLA-63(R, R) and GLA-64(R, R)], and 3-O-[(3R)-3-(acyloxy)tetradecanoyl]-2-deoxy-4-O-phosphono-2-tetradecanamido-D-glucose [GLA-67(R), GLA-68(R) and GLA-69(R)] have been synthesized. Benzyl 2-[(3R)-3-(benzyloxymethoxy)tetradecanamido]-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (5) and benzyl 2-deoxy-4,6-O-isopropylidene-2-tetradecanamido-β-D-glucopyranoside (6) were each esterified with (3R)-3-dodecanoyloxytetradecanoic acid (1), (3R)-3-tetradecanoyloxytetradecanoic acid (2) or (3R)-3-hexadecanoyloxy-tetradecanoic acid (3), to give 7-11, which were then transformed, by the sequence of deisopropylidenation, 6-O-tritylation and 4-O-phosphorylation, into a series of desired compounds.     

Novel Disaccharides Containing 3-Deoxy-D-Manno-2-Octulosonic Acid (KDO) and Lipid a Subunit Analogs

Abstract

3-Deoxy-D-manno-2-octulosonic acid (KDO)₁ is a prominent constituent of bacterial lipopolysaccharides (LPS),₂ and recently it has been demonstrated _3,4 that the KDO part in the core region of LPS is α-ketosidically linked to 0-6′ of the o-glucosamine-disaccharide backbone of lipid A. Although the portion, including KDO, has been suggested_5,6 to be necessary for expression of antitumor and interleukin 1 (IL 1)-induction activities of LPS, the disticnt biological roles of KDO in LPS are still obscure.     

Spontaneous formation of mesoporous silica films using non-surfactant template, and optimization with Doehlert designs, for adsorbent for polycyclic aromatic hydrocarbons

To prepare mesoporous silica thin-films by a simple and environmentally friendly pathway, spontaneous formation of silica thin-films in a sol–gel solution without surfactants was studied. The silica thin-films were prepared by immersing a glass substrate, such as a cylindrical test-tube, into a sol–gel solution containing tetraethoxysilane, water, acetic acid, 2-propanol, and triethylene glycol as a pore-forming agent. The resulting thin-films were transparent. The presence of mesopores was confirmed by field-emission scanning electron microscopy, atomic-force microscopy and nitrogen adsorption–desorption isotherms. The Barrett–Joyner–Halenda plot from the adsorption branch of the isotherms indicated that the pore diameter was 2.6 nm. To illustrate the potential use of the film as an adsorbent, the extraction of polycyclic aromatic hydrocarbons was conducted using the chemically modified silica thin-film coated on a test-tube. The composition of the sol–gel solution was optimized using experimental design, i.e., Doehlert design, and recovery of polycyclic aromatic hydrocarbons.     

Reversible Pore Size Control of Elastic Microporous Material by Mechanical Force

Nanoporous materials, such as zeolites, activated carbons, and metal–organic frameworks (MOFs), are peculiar platforms in which a variety of guest molecules are stored, reacted, and/or separated. The size of the nanopores is essential to realize advanced functions. In this work, we demonstrate a very simple but innovative method for the control of nanopore size, that is, reversible and continuous control by mechanical force loaded to soft nanoporous materials. The elastic properties of several microporous materials, including zeolites, zeolite‐templated carbon (ZTC), activated carbon, and MOFs (e.g., ZIF‐8), are examined and it is found that ZTC is a material that is suitable for the aforementioned idea thanks to its extraordinary soft properties compared to the others. The original pore size of ZTC (1.2 nm) can be contracted to 0.85 nm by using a relatively weak loading force of 135 MPa, whereas the other microporous materials barely contracted. To demonstrate the change in the physical properties induced by such artificial deformation, in situ gas adsorption measurements were performed on ZTC with and without loading mechanical force, by using CO₂, CH₄, and H₂, as adsorbates. Upon the contraction by loading 69 or 135 MPa, CO₂ adsorption amount is increased, due to the deepening of the physisorption potential well inside the micropores, as proved by the increase of the heat of adsorption. Moreover, the adsorption amount is completely restored to the original one after releasing the mechanical force, indicating the fully reversible contraction/recovery of the ZTC framework against mechanical force. The experimental results are theoretically supported by a simulation using Grand Canonical Monte Carlo method. The similar adsorption enhancement is observed also on CH₄, whereas H₂ is found as an exception due to the weak interaction potential.     

Some characterizations of minimally thin sets in a cylinder and Beurling-Dahlberg-Sjögren type theorems

This paper shows that some characterizations of minimally thin sets connected with a domain having smooth boundary and a half-space in particular can also be given for a minimally thin set at infinity of a cylinder.