Kazunori Matsuura

Analysis of GM3-Gg3 interaction using clustered gycoconjugate models constructed from glycolipid monolayers and artificial glycoconjugate polymers

Carbohydrate-carbohydrate interactions between clustered GM3 on the Langmuir monolayer and clustered Gg3 trisaccharide along a polystyrene chain were investigated using surface pressure-area (π-A) isotherms and surface plasmon resonance (SPR). The π-A isotherm of the GM3 monolayer was expanded substantially and specifically by the Gg3-trisaccharide-bearing glycoconjugate polystyrene [PN(Gg3)] even at 10−12 M. The PN(Gg3)-induced expansion of the GM3 monolayer required no calcium ion, and the expansion was strongly inhibited in the presence of urea and acetamido sugars. SPR studies of the GM3-Gg3 interaction were carried out to estimate the affinity constant and specificity of the interaction quantitatively. PN(Gg3) was adsorbed onto the GM3 monolayer strongly and specifically with an apparent affinity constant of Ka = 2.5 × 106 M−1. The mechanism of the GM3-Gg3 interaction was discussed on the basis of the relationship between affinity and structure. We found that the NHAc groups of N-acetylneuraminic acid in GM3 and of GalNAc in Gg3 play an important role in the GM3-Gg3 interaction and that PN(Gg3) recognizes not only some specified portions of GM3 but also the trisaccharide as a whole. Published in 2004.

Phosphoramidite solid-phase synthesis of site-specifically glycosylated oligodeoxynucleotides

Abstract A galactose-modified deoxyuridine phosphoramidite was synthesized via the Heck reaction and applied to solid-phase synthesis to provide a new type of oligo DNA–galactose conjugates, which maintained stringent base-pairing fidelity for unique DNA sequences.

Spontaneous self-assembly of nanospheres from trigonal conjugate of glutathione in water

A novel C3-symmetric peptide conjugate bearing three glutathione units (trigonal-glutathione, TG) was synthesized and its self-assembling behavior in water was studied by dynamic light scattering measurement, electron microscopy, and 1H-NMR spectroscopy. In water, TG showed spontaneous self-assembly into nanospheres with the size of 100–250 nm. The size of TG assemblies is minimally affected by the concentration and pH. Concentration dependence of 1H-NMR chemical shifts in D2O revealed that TG is self-assembled by interactions between glutathione units (hydrogen bonding, electrostatic interactions) with an apparent association constant of Ka = 6.36 × 103 M−1. Concentration dependence of light scattering intensity and guest-binding ability indicated that the nanospheres underwent structural changes from hollow to filled spheres depending on the concentration.

Trigonal tryptophane zipper as a novel building block for pH-responsive peptide nano-assemblies

A novel C(3)-symmetric peptide conjugate bearing tryptophane zipper-forming peptides showed pH-responding self-assembly into nanospheres and nanofibers in water.

Tris-bipyridine ruthenium complex-based glyco-clusters: amplified luminescence and enhanced lectin affinities

Abstract Tris-bipyridine ruthenium complexes carrying hexavalent α-glucoside, α-mannoside, and β-galactoside clusters were synthesized. Isomeric Λ- and Δ-complexes were separated, and their optical and conformational characteristics were investigated by UV–vis, CD, luminescence, and NMR spectroscopies as well as molecular dynamics calculation. The complexes exhibited strong luminescence and also strong inhibition of lectin-induced hemagglutination: particularly, the binding of hexavalent mannose cluster complexes to concanavalin A was strong.

A Quartz-crystal microbalance study of adsorption behaviors of artificial glycoconjugate polymers with different saccharide chain lengths and with different backbone structures

Adsorption of glycopolymers is essential for the development of biologically active surfaces employing oligosaccharides as recognition signals. The adsorption behavior has been investigated by quartz-crystal microbalances (QCMs) with use of two different series of glycopolymers: (1) polystyrenes carrying maltooligosaccharides with different saccharide lengths and (2) lactose-carrying polymers with polystyrene and polyphenylacrylamide main chain structures. These glycopolymers were adsorbed on the hydrophobic surfaces of self-assembled monolayers (SAM) of 1-octadecanethiol and cast films of polystyrene from their aqueous solutions, but not on hydrophilic surfaces of SAM of cystamine hydrochloride. The apparent association constants (K a = 10 4 ∼ 10 6 M -1 in molarity of the monomeric unit) and maximum adsorption amounts (Δm max ) on 1-octadecanethiol SAMs and polystyrene cast films were estimated from the Langmuir adsorption isotherms. These values depended on the side-chain oligosaceharide lengths and the main chain chemical structures of these glycopolymers. The adsorption behavior has been discussed in correlation with the desorption of the adsorbed polymer in an aqueous surfactant solution, the partition of the glycopolymer in a water/1-octanol system, and the adsorption amont of bovine serum albumin (BSA) onto the glycopolymer-adsorbed surface. We propose that these polymers are adsorbed in loop-train-tail conformations in which the ratio of the loop-tail portion to the train portion depends on the hydrophilic-hydrophobic property of the polymers.

Inclusion of Zinc Oxide Nanoparticles into Virus-Like Peptide Nanocapsules Self-Assembled from Viral β-Annulus Peptide

A viral β-annulus peptide connected with a zinc oxide (ZnO)-binding sequence (HCVAHR) at its N-terminal was synthesized, and the inclusion behavior of quantum-sized ZnO nanoparticles into the peptide nanocapsules formed by self-assembly of the peptide in water was investigated. Dynamic light scattering (DLS) measurements showed that ZnO nanoparticles (approximately 10 nm) in the presence of the peptide (0.1 mM) formed assemblies with an average size of 48 ± 24 nm, whereas ZnO nanoparticles in the absence of the peptide formed large aggregates. Transmission electron microscopy (TEM) observations of the ZnO nanoparticles in the presence of the peptide revealed that ZnO nanoparticles were encapsulated into the peptide nanocapsules with a size of approximately 50 nm. Fluorescence spectra of a mixture of the peptide and ZnO nanoparticles suggested that the ZnO surface and the peptide interact. Template synthesis of ZnO nanoparticles with the peptide nanocapsules afforded larger nanoparticles (approximately 40 nm), which are not quantum-sized ZnO.

Syntheses and Self-assembling Behaviors of Pentagonal Conjugates of Tryptophane Zipper-Forming Peptide

Pentagonal conjugates of tryptophane zipper-forming peptide (CKTWTWTE) with a pentaazacyclopentadecane core (Pentagonal-Gly-Trpzip and Pentagonal-Ala-Trpzip) were synthesized and their self-assembling behaviors were investigated in water. Pentagonal-Gly-Trpzip self-assembled into nanofibers with the width of about 5 nm in neutral water (pH 7) via formation of tryptophane zipper, which irreversibly converted to nanoribbons by heating. In contrast, Pentagonal-Ala-Trpzip formed irregular aggregates in water.

CTAB-induced morphological transition of DNA micro-assembly from filled spheres to hollow capsules

DNA microspheres formed by self-assembly of DNA three-way junctions with self-complementary sticky-ends undergo an unexpected dynamic transformation from filled spheres into hollow capsules upon addition of cationic surfactants such as cetyltrimethylammonium bromide.

Peptide nanospheres self-assembled from a modified β-annulus peptide of sesbania mosaic virus

A novel β‐annulus peptide of Sesbania mosaic virus bearing an FKFE sequence at the C terminus was synthesized, and its self‐assembling behavior in water was investigated. Dynamic light scattering and transmission electron microscopy showed that the β‐annulus peptide bearing an FKFE sequence self‐assembled into approximately 30 nm nanospheres in water at pH 3.8, whereas the β‐annulus peptide without the FKFE sequence afforded only irregular aggregates. The peptide nanospheres possessed a definite critical aggregation concentration (CAC = 26 μM), above which the size of nanospheres were nearly unaffected by the peptide concentration. The formation of peptide nanospheres was significantly affected by pH; the peptide did not form any assemblies at pH 2.2, whereas larger aggregates were formed at pH 6.4–11.6.