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Shigeru Matsuoka

Publications and source records attributed to Shigeru Matsuoka.

12 recordsLinked to original sources
PubMed2006

Double-quantum filtered rotational-echo double resonance.

The homonuclear scalar coupling of a directly bonded 13C-13C pair has been used to create a double-quantum filter (DQF) to remove the natural-abundance 13C background in 13C{15N} rotational-echo double-resonance (REDOR) experiments. The DQF scalar and REDOR dipolar evolution periods are coincident which is important for sensitivity in the event of weak 13C-15N dipolar coupling. Calculated and observed 13C{15N} DQF-REDOR dephasings were in agreement for a test sample of mixed recrystallized labeled alanines. Glycine metabolism in a single uniform-15N soybean leaf labeled for 6 min by 13CO2 was measured quantitatively by 13C{15N} DQF-REDOR with no background interferences.

Algorithms↗
PubMed2006

Structures of new amphidinols with truncated polyhydroxyl chain and their membrane-permeabilizing activities.

Two new homologues of amphidinols (AM14 and AM15) were isolated from the cultured dinoflagellate Amphidinium klebsii. The structures were elucidated on the basis of 2D NMR and collision-induced dissociation MS/MS and turned out to be closely related homologues of AM7. Their weak membrane-disrupting activity indicates that the hydrophobic polyene chain is essential for the potent biological activities. Structure-activity relationship for the polyhydroxyl part was then examined with use of AM homologues possessing various chain lengths, indicating that the pore size of the channel/lesion formed by AMs was not greatly affected by the length of the polyhydroxyl chain.

Alkenes↗
PubMed2006

Membrane interaction of amphotericin B as single-length assembly examined by solid state NMR for uniformly 13C-enriched agent.

The membrane interaction of amphotericin B (AmB), one of the most important anti-fungal drugs, was investigated by solid state NMR measurements of uniformly 13C-enriched AmB, which was prepared by the culture of the drug-producing microorganism in the presence of [u-13C6]glucose. All the 13C NMR signals of AmB upon binding to DLPC membrane were successfully assigned on the basis of the 13C-13C correlation spectrum. 13C-31P RDX (Rotational-Echo Double Resonance for X-clusters) experiments clearly revealed the REDOR dephasing effects for carbon atoms residing in the both terminal parts, whereas no dephasing was observed for the middle parts including polyolefinic C20-C33 and hydroxyl-bearing C8/C9 parts. These observations suggest that AmB binds to DLPC membrane with a high affinity to the phospholipid and spans the membrane with a single molecular length.

Amphotericin B↗
PubMed2005

Ladder-shaped polyether compound, desulfated yessotoxin, interacts with membrane-integral alpha-helix peptides.

Ladder-shaped polyether compounds, represented by brevetoxins, ciguatoxins, maitotoxin, and prymnesins, are thought to possess the high affinity to transmembrane proteins. As a model compound of ladder-shaped polyethers, we adopted desulfated yessotoxin (2) and examined its interaction with glycopholin A, a membrane protein known to form a dimer or oligomer. Desulfated yessotoxin turned out to interact with the alpha-helix so as to induce the dissociation of glycopholin oligomers when examined by SDS and PFO gel electrophoresis. The results provided the first evidence that ladder-shaped polyethers interact with transmembrane helix domains.

Amino Acid Sequence↗
PubMed2005

Dominant formation of a single-length channel by amphotericin B in dimyristoylphosphatidylcholine membrane evidenced by 13C-31P rotational echo double resonance.

(13)C-Labeled amphotericin B (AmB) was prepared by feeding the producing organism Streptomyces nodosus with [3-(13)C]propionate. The REDOR experiments for dimyristoylphosphatidylcholine (DMPC) membrane using the (13)C-labeled AmB showed the prominent dephasing effects between the phosphate group in PC and C41 carboxyl carbon in the polar head. In addition, C39/C40 methyl carbons also gave rise to the significant reduction of their (13)C NMR signals, implying that both terminal parts of AmB reside close to the surface of the DMPC membrane. Conversely, the same REDOR experiments with use of distearoylphosphatidylcholine (DSPC) showed no dephasing for the C39/C40 methyl signals while a marked reduction of the C41 carbonyl signal was again observed. These findings should be most reasonably accounted for by the notion that AmB can span across the DMPC membrane with a single-length interaction but cannot span the DSPC membrane due to its greater thickness. To our knowledge, the results provide the first direct spectroscopic evidence for the formation of a single-length channel across a biomembrane, which was previously suggested by channel current recording experiments.

Amphotericin B↗
PubMed2004

Membrane-permeabilizing activities of amphidinol 3, polyene-polyhydroxy antifungal from a marine dinoflagellate.

Amphidinols, which are polyene-polyhydroxy metabolites produced by the marine dinoflagellate Amphidinium klebsii, possess potent antifungal and hemolytic activities. The membrane permeabilizing actions of amphidinol 3, the most potent homologue, were compared with those of polyene antibiotics, amphotericin B (AmB) and filipin, in hemolytic tests, 23Na nuclear magnetic resonance (NMR)-based membrane permeabilizing assays, and UV spectroscopy for liposome-bound forms. In Na+ flux experiments using large unilamellar vesicles (LUVs), ion efflux by amphidinol 3 was inhibited by cholesterol or ergosterol, which was opposed to previous results [J. Mar. Biotechnol., 5 (1997) 124]. When the effect of the agents on the size of vesicles was examined by light scattering experiments, amphidinol 3 did not significantly alter their size while filipin and synthetic detergent Triton X-100 did. The observations implied that the activity of amphidinol 3 was mainly due to formation of large pores/lesions in liposomes rather than detergent-like disruption of membrane. The pore/lesion size was estimated to be 2.0-2.9 nm in diameter on the basis of osmotic protection experiments using blood cells. The UV spectra in liposomes, which revealed the close interaction of polyene moieties in a lipid bilayer, further implied that the membrane activity of amphidinol 3 is caused by the molecular assemblage formed in biomembrane. These results disclose that amphidinol 3 is one of few non-ionic compounds that possess potent membrane permeabilizing activity with non-detergent mechanism.

Alkenes↗
PubMed2004

An amphotericin B-ergosterol covalent conjugate with powerful membrane permeabilizing activity.

Amphotericin B-sterol conjugates were synthesized and examined for their membrane permeabilizing activity. Ergosterol and cholesterol, each connected with amphotericin B via an ethylenecarbamate or hexamethylenecarbamate linker, were examined by K(+) flux assays using liposomes and by single-channel recording across phospholipid membrane. Among four conjugates tested, AmB-ergosterol bearing an ethylenecarbamate linker exhibited the most powerful activity, which substantially exceeded that of the cholesterol homolog. Single-channel recording clearly exhibited that the ergosterol conjugate elicited channel current with the conductance of 28 pS, which was comparable with those by AmB, and revealed a higher channel open probability than the cholesterol conjugate. These results imply that direct interaction between amphotericin B and ergosterol is reproduced by their conjugate, which may serve as a model compound for understanding the drug's selective toxicity.

Amphotericin B↗
PubMed2003

Membrane permeabilizing activity of amphotericin B is affected by chain length of phosphatidylcholine added as minor constituent.

The effect of acyl-chain length of phospholipid on the membrane permeabilizing activity of amphotericin B (AmB) was examined using egg phosphatidylcholine (eggPC) liposomes containing 5% or 20% phosphatidylcholine with various lengths of fatty acyl chains from C(10) to C(18); 1,2-dicapryloyl-sn-glycero-3-phosphocholine (DCPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC). The membrane activity of AmB was evaluated by two methods; the drug was added to a liposome suspension (added-via-aqua), or mixed with lipids prior to liposome preparation (mixed-with-lipid). In both cases, K(+) influx by AmB was measured as pH change inside liposomes by 31P-NMR. The C(10) and C(12) acyl phospholipids markedly enhanced the activity of AmB, the C(14) and C(16) lipids virtually showed no effect, and the C(18) lipid was inhibitory to the AmB's action. Clear distinction between the C(12) and C(14) lipids, which differ only in acyl chains by two carbons, implies that molecular interaction between phospholipid and AmB is partly due to the matching of their hydrophobic length.

Acylation↗
PubMed2002

Cholesterol markedly reduces ion permeability induced by membrane-bound amphotericin B.

It is widely accepted that amphotericin B (AmB) together with sterol makes a mixed molecular assemblage in phospholipid membrane. By adding AmB to lipids prior to preparation of large unilamellar vesicles (LUV), we directly measured the effect of cholesterol on assemblage formation by AmB without a step of drug's binding to phospholipid bilayers. Potassium ion flux assays based on 31P-nuclear magnetic resonance (NMR) clearly demonstrated that cholesterol markedly inhibits ion permeability induced by membrane-bound AmB. This could be accounted for by a membrane-thickening effect of cholesterol since AmB actions are known to be markedly affected by the thickness of membrane. Upon addition of AmB to an LUV suspension, the ion flux gradually increased with increasing molar ratios of cholesterol up to 20 mol%. These biphasic effects of cholesterol could be accounted for, at least in part, by the ordering effect of cholesterol.

Amphotericin B↗
PubMed2002

Amphotericin B dimers with bisamide linkage bearing powerful membrane-permeabilizing activity.

[structure: see text] Covalently linked dimers of amphotericin B were prepared by cross-linking its carboxylic acid. Among these, a dimer with a linkage of 1,6-hexanediamine revealed potent hemolytic activity (EC50, 0.25 microM) while its N-acetyl derivative gave rise to large K+ ion flux in phosphatidylcholine liposomes, regardless of the presence or absence of sterols, suggesting that the dimers may serve as a tool for elucidating the structure of the ion channel assemblage formed by amphotericin B.

Amphotericin B↗
PubMed2002

Amphotericin B covalent dimers forming sterol-dependent ion-permeable membrane channels.

Polyenemacrolides such as amphotericin B (AmB) were thought to assemble together and form an ion channel across plasma membranes. Their antimicrobial activity has been accounted for by this assemblage, whose stability and activity are dependent on sterol constituents of lipid bilayer membranes. The structure of this channel-like assemblage formed in biomembranes has been a target of extensive investigations for a long time. For the first step to this goal, we prepared several AmB dimers with various linkers and tested for their channel-forming activity. Among these, AmB dimers that bore an aminoalkyl-dicarboxylate tether covalently linked between amino groups of AmB showed potent hemolytic activity. Furthermore, K+ influx actions monitored by measuring the pH of the liposome lumen by 31P NMR revealed that the dimers formed the molecular assemblage similar to that of AmB in phospholipid membrane. Judging from changes in 31P NMR spectra, the dimers appeared to induce "all-or-none"-type ion flux across the liposome membrane in the presence of ergosterol, which suggested that the ion channel formed by ergosterol/dimer is similar to that of AmB. With these data in hand, we are now trying to elucidate the structure of the ion-channel complex by making the labeled conjugates of AmB for NMR measurements.

Amphotericin B↗