Takashi Terabayashi

Quantitative measurements of the interaction between monosialoganglioside monolayers and wheat germ agglutinin (WGA) by a quartz-crystal microbalance

Monosialogangliosides (GM1, GM2, GM3 and GM4) were reconstituted in lipid monolayers at the air-water interface. The binding amounts and the initial binding rates of wheat germ agglutinin (WGA) to the monosialoganglioside monolayers were quantitatively studied by use of a quartz-crystal microbalance (QCM). A QCM was horizontally attached to the monolayer from the air phase, and the binding behavior (mass increase) was followed by the frequency decrease of the QCM. WGA binding affinities for the ganglioside monolayers were influenced by hydrophilic head groups of lipid matrices, densities of gangliosides, and sequences of oligosaccharide in gangliosides. Binding of WGA to the gangliosides reconstituted in a phosphatidylcholine (sphingomyelin and distearoylphosphatidylcholine) matrix was strongly suppressed, but not in a neutral glycolipids (GlcCer, GalCer, and LacCer), dipalmitoylphosphatidylethanolamine, and dipalmitoylphosphatidylethanolamine matrix. WGA showed high affinity for monolayers containing 20 mol% gangliosides, but only low affinity for 100% ganglioside monolayers. WGA preferably binds to gangliosides in the following sequence: GM3 > GM4 >> GM2 = GM1. No affinities of WGA for GM2 and GM1 were observed. The combined techniques of monolayer and QCM have the advantages of investigating recognition properties of gangliosides.

Naturally occurring ganglioside lactones in Minke whale brain.

Ganglioside lactones in Minke whale brain were analysed. In order to exclude the possibility of the artificial lactonization of gangliosides during the analytical procedures, lactone species were separated from their parent gangliosides at an early stage by DEAE-Sephadex A-25 column chromatography using a stepwise elution. Applying the improved method, GM41 lactones were found in grey and white matters of cerebrum and cerebellum, while GD3 monolactone was found only in cerebellar gray matter. The concentration of each ganglioside lactone was one thousandth of the parent ganglioside.

Analysis of oligo- and poly-N-acetylneuraminic acids and their lactones by capillary electrophoresis

Abstract The present work establishes the separation procedure from fragments of colominic acid, a mixture of homopolymers of N-acetylneuraminic acid (NeuAc), and their lactones by capillary electrophoresis. Using borate buffer containing sodium dodecyl sulfate and methyl cellulose, colominic acid can be separated up to triacontamer of NeuAc by capillary electrophoresis. The method can also separate lactones and enzymic degradation products of NeuAc oligomers.

Negative circular dichroism (CD) band of lactones of sialic acid polymers observed at 235 nm

Abstract NeuAc oligomers and polymers (DP2-15), isolated from a commercial colominic acid, were lactonized in 10 mM HCl or glacial acetic acid. All lactonized oligo/ polymers showed a negative circular dichroism (CD) band at 235 nm. The determination of lactonized oligo/polymer was performed by capillary electrophoresis. Molar ellipticity per lactone ring was −1.5 × 10 4 deg·cm 2 /dmol, and the molar ellipticity showed additivity with respect to the lactone ring.

A comparative study on ceramide compisition of cetacean brqain gangliosides

1. Ceramide composition and N-glycolylneuraminic acid content of gangliosides from gray and white matters and myelin of cerebrum and cerebellum were analyzed in eight species belonging to the suborder Odontoceti and two species to Mystacoceti. 2. The most characteristic feature was high contents of C20:0 (10-40%) and C24 species (5-40%). 3. Content of hydroxy fatty acid of C24 species was higher in cerebellum (5-20%) than cerebrum (0-3%). 4. Major component of long-chain base was dC18:1 (70-90%). 5. N-glycolylneuraminic acid was found in sperm whale, Dalls porpoise and killer whale (0.1-1.7%).

The characteristic negative Cotton effect of ganglioside lactones observed by circular dichroism spectrometry

Circular dichroism spectrometry was applied to gangliosides and their lactones and revealed that the lactones have a characteristic strong negative Cotton effect around 235 nm. Four monolactones and two dilactones, which were formed from GM4, GD3, and GD1b, gave molar ellipticities at the wavelength in magnitude of 10(4), while their parent gangliosides, along with other gangliosides such as GM3, GM1, GD1a, GT1b, and GQ1b, showed no distinct feature. Two ganglioside esters, GM4-methyl ester and O-Ac-GT1b did not show the Cotton effect. The molar ellipticities had an additivity with respect to the number of lactone rings. The Cotton effect was attributed to the carbonyl group on the lactone ring.

Observation of ganglioside lactone formation with CD spectrometry

Monolactone (NeuAc1-9NeuAc linkage) formation of a ganglioside, GD1b, was observed at 20 degrees C on solutions ranging in concentration from 0.008 to 1.7 mM and in pH from 2 to 8.1, by following the change of ellipicity at 235 nm, where lactonized gangliosides showed a strong Cotton effect. The lactonization was found to be a first-order reaction in both GD1b and H+ in the initial stage but was affected later by a backward reaction, hydrolysis of the lactone linkage. The rate constant was 0.08 h-1 at pH 3. At this pH the reaction went close to equilibrium in 24 h at approximately 70% lactonization. At pH higher than 5.9 no change was observed in the ellipticity within 30 h, suggesting the possibility that at most 0.6% of the ganglioside lactonized. Lactonization of another ganglioside, GD3, in glacial acetic acid was observed with a 0.2-mm cell, agreeing well with a reported result.

Brain gangliosides of cetaceans

Abstract 1. 1. Ganglioside contents and compositions of gray matter, white matter and myelin cerebrum and cerebellum were invetigated on nine species of cetaceans (eight species belonging to the suborder Odontoceti and one species to Mystacoceti). 2. 2. The patterns of ganglioside compositions were divided into two groups. The patterns for six species belonging to the family Delphinidae were different from that of other species, which contained higher amount of GM4 in white matter and myelin.