Publications by authors named "Tokutake N"

Elderly patients tend to have troubles with oral conditions such as the impairment of deglutition capability (difficulty in swallowing), in addition to a decline in physical performance. An air extruded jelly formulation (AEJF) has been developed as a new formulation consisting of jelly and clean air under increased pressure. As jelly is discharged smoothly by pushing the air portion, elderly patients are able to easily take jelly from the package.

View Article and Find Full Text PDF

Lipid-lipid interactions across cholesterol-rich phospholipid bilayers were investigated by measuring nearest-neighbor preferences of exchangeable phospholipids derived from 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), in the presence of nonexchangeable dimers (i.e., templates) made from DMPE or DSPE.

View Article and Find Full Text PDF

The mixing behavior of a phospholipid containing a cis-cyclopropyl moiety (1) with one that contains two myristoyl groups (3a) has been investigated in fluid bilayers via the nearest-neighbor recognition (NNR) method. In the absence of cholesterol, these lipids mix ideally. In the presence of cholesterol, they show a modest preference for homo-phospholipid association.

View Article and Find Full Text PDF

Nearest-neighbor recognition experiments, which have been carried out using exchangeable dimers derived from 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine,and 1-palmitoyl-2-oleoyl-sn-glycerophosphoethanolamine, indicate that replacement of H2O by D2O can significantly influence phospholipid mixing, but only in bilayers that are saturated and devoid of cholesterol. These findings, together with those of previous electron spin resonance spin-labeling studies,indicate that mammalian membranes, which are rich in cholesterol and unsaturated phospholipids, are ideal hydrophobic barriers.

View Article and Find Full Text PDF

Nearest-neighbor recognition studies have revealed that favored sterol-phospholipid associations can be reversed in a fluid bilayer that contains relatively long (high melting) and short (low melting) phospholipids, when the sterol content is sufficiently high; that is, like-lipids now become favored nearest-neighbors. A possible origin of this effect is briefly discussed.

View Article and Find Full Text PDF

Lipid-lipid interactions across a phospholipid bilayer were probed by measuring the nearest-neighbor preferences of exchangeable phospholipid monomers derived from 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) in the presence of nonexchangeable DMPE- or DSPE-based dimers. Each of these permanent dimers promoted homophospholipid association to the same extent, whereas the corresponding nonexchangeable monomers were without effect. These results support a model in which the longer phospholipids in one monolayer leaflet preferentially associate with shorter ones in the adjoining monolayer.

View Article and Find Full Text PDF

The results of nearest-neighbor recognition experiments that have been carried out with exchangeable dimers derived from 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine, in the presence of cholesterol, dihydrocholesterol, coprostanol, cholestane, cholesteryl methy ether, and sitosterol, provide strong support for a condensing mechanism in which the flexible acyl chains of the phospholipids complement, perfectly, the shape of neighboring sterols, thereby leading to a high number of hydrophobic contacts and tight packing.

View Article and Find Full Text PDF

Nearest-neighbor recognition measurements have established that the effects of deuterium substitution on phospholipid mixing are exceedingly small. Thus, the mixing behavior of an exchangeable phospholipid bearing two stearoyl chains with a homologue containing two myristoyl chains in gel-fluid bilayers, fluid bilayers, cholesterol-rich fluid bilayers, and gel-fluid bilayers that have been enriched with cholesterol correspond to a difference in the free energy of mixing that is less than 2.2 cal/mol of hydrogen in all cases.

View Article and Find Full Text PDF

Alendronate (alendronate sodium hydrate; Bonalon Tablet, 5 mg) is a nitrogen-containing bisphosphonate, which combines with the bone surface and reduces osteoclast-mediated bone resorption. It is a third-generation bisphosphonate compound, specifically distributed on the surface of bone resorption and taken into osteoclasts. Under the closed circumstances which is formed with osteoclast and the bone surface, alendronate becomes detached from the bone surface and taken into osteoclast since acid released from osteoclast leads to pH decrease (acidified).

View Article and Find Full Text PDF

A series of sulfoximine-based transition-state analogue inhibitors with a varying alkyl side chain was synthesized to probe the recognition of a Cys substrate by E. coli gamma-glutamylcysteine synthetase (gamma-GCS). The sulfoximines with a small alkyl group (H, methyl, ethyl, propyl, butyl and CH2OH) each served as a slow-binding inhibitor, the sulfoximine with an ethyl being by far the most potent inhibitor to cause facile and irreversible enzyme inhibition.

View Article and Find Full Text PDF

Using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon, enantioselective deprotonation of prochiral 4-substituted cyclohexanones in the presence of excess trimethylsilyl chloride was examined in THF in the absence and in the presence of HMPA. It is shown that enantioselectivity of the reactions decreases as the substituent on the chiral carbon of the chiral lithium amides and the substituent at the 4-position of cyclohexanones become reasonably bulky. An eight-membered cyclic transition state model is proposed for this deprotonation reaction.

View Article and Find Full Text PDF

The Deltadelta (deltaS-deltaR) values for the C-1 methyl 1H signals in the 1H-NMR spectroscopy of the bis-MTPA esters of four synthetic stereoisomers of alkane-6,8-diols, viz., bis-MTPA esters of (6S,8R)-C27- (1a) and C29- (3a) (Deltadelta = -0.05 ppm), (6R,8S)-C27- (2a) and C29- (4a) (Deltadelta = +0.

View Article and Find Full Text PDF

Phosphinic acid-, sulfoximine- and sulfone-based transition-state analogues were synthesized and evaluated as inhibitors of Escherichia coli gamma-glutamylcysteine synthetase. These compounds have a carboxyl function at the beta-carbon to the tetrahedral central hetero atom so as to mimic the carboxyl group of the attacking cysteine in the transition state. The phosphinic acid- and the sulfoximine-based compounds were found to be potent ATP-dependent inactivators, both showing a slow-binding kinetics with overall affinities and second-order inactivation rates of one to two orders of magnitude greater than those of L-buthionine (SR)-sulfoximine (L-BSO).

View Article and Find Full Text PDF

The structural factors of antimycin A molecule required for inhibitory action were studied using newly synthesized antimycin A derivatives with bovine heart submitochondrial particles, in order to probe the interaction between antimycin A and its binding site. In particular, we focused upon the roles of the amide bond bridge, which connects the salicylic acid and dilactone ring moieties, and the 3-formylamino group in the salicylic acid moiety. The lack of formation of an intramolecular hydrogen-bond between phenolic OH and amide carbonyl groups resulted in a remarkable loss of the activity (by four orders of magnitude), indicating that this hydrogen-bond is essential for the inhibition.

View Article and Find Full Text PDF

A series of antimycin A analogues was synthesized by modifying the salicylic acid moiety, whereas the portion of the molecule corresponding to the natural dilactone-ring moiety was fixed as di-n-octyl L-glutamate. To probe the structure of the antimycin A binding site, the structural factors of the salicylic acid moiety required for inhibitory action were examined by means of structure-activity studies with intact rat-liver mitochondria and the cytochrome bc1 complex isolated from bovine heart mitochondria. As suggested earlier (Rieske, J.

View Article and Find Full Text PDF

Four modified cytochrome b's carrying mononucleotide substitutions affecting center N residues were analysed. The mutant carrying a G33D change does not incorporate heme into the apocytochrome b and fails to grow on non-fermentable carbon sources. Out of 85 genetically independent revertants derived from this mutant, 82 were true back-mutants restoring the wild type sequence (D33G).

View Article and Find Full Text PDF

A series of antimycin A analogs was synthesized by replacement of a dilactone-ring moiety of natural antimycin A by various alkyl, substituted phenyl, substituted diphenyl ether, or amino acid ester groups. The structure-inhibitory activity relationship was studied with rat-liver mitochondria to identify roles of the dilactone-ring moiety in the inhibitor binding to a Qi reaction center of cytochrome bc1 complex. All derivatives caused further reduction of cytochrome b reduced by succinate and the oxidant-induced reduction, showing that the derivatives inhibited electron transport by interacting with a Qi reaction center.

View Article and Find Full Text PDF

The respiration inhibitory effects of the inhibitory uncouplers, 2,6-diiodo-4-(2,2-dicyanovinyl)phenol and 2,6-dimethoxy-4-(2,2-dicyanovinyl)phenol, the binding site of which is cytochrome bc1 (cyt. bc1) complex, were studied with rat-liver mitochondria. The inhibitory potency of 2,6-diiodo-4-(2,2-dicyanovinyl)phenol and of 2,6-dimethoxy-4-(2,2-dicyanovinyl)phenol was increased and decreased, respectively, by steep dissipation of the transmembrane electrical potential after adding the potent uncoupler, fluazinam, the uncoupling activity of which disappears with time.

View Article and Find Full Text PDF

The respiration inhibition of rat-liver mitochondria by a series of substituted phenolic uncouplers was studied. The inhibitory effects were classified into three types, I-III, depending on the pattern of the changes in inhibitory potency observed when the potent uncoupler SF6847 was simultaneously applied. The extent of inhibition by type I phenols did not change as the transmembrane potential was dissipated by SF6847, but the extent of inhibition by type II and III phenols was decreased and increased, respectively.

View Article and Find Full Text PDF

The uncoupling potency of a series of substituted phenols with rat-liver mitochondria was analyzed quantitatively with physicochemical substituent and molecular parameters such as log P, P being the partition coefficient in a phosphatidylcholine liposome/water system, log KA, KA being the acid dissociation constant, and the Taft-Kutter-Hansch steric constant, Es, for ortho-substituents. The potency evaluated from the concentration in the medium required for a defined response was analyzed, showing that the incorporation of compounds in terms of log P, a certain balance between neutral and ionized forms expressible by a parabolic function of log KA and the steric shielding effect of the ortho-substituents on the negatively charged center of ionized form are highly significant factors governing the variations in potency. The potency was also quantitatively separated into the intrinsic potency as the protonophore inside the inner mitochondrial membrane and the incorporation factor in terms of log P.

View Article and Find Full Text PDF