Bioscience, Biotechnology, and Biochemistry
Online ISSN : 1347-6947
Print ISSN : 0916-8451
Volume 68 , Issue 11
Showing 1-33 articles out of 33 articles from the selected issue
Review
  • Kengo KANAMARU, Kan TANAKA
    2004 Volume 68 Issue 11 Pages 2215-2223
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Chloroplast transcription in higher plants is performed by two types of RNA polymerases, plastid-encoded RNA polymerase (PEP) and nuclear-encoded RNA polymerase (NEP). PEP is a eubacteria-type multisubunit enzyme whose catalytic core subunits are encoded by the chloroplast genome, whereas NEP is the nuclear encoded T7 phage-type single subunit enzyme. PEP is critical for the biogenesis and maintenance of chloroplasts, and is finely tuned by the nuclear encoded sigma subunits. Of the six Arabidopsis sigma subunits, SIG2 is involved in the transcription of several chloroplast tRNA genes, including trnE encoding tRNA-Glu. SIG2 possibly couples translation and pigment synthesis in chloroplasts. On the other hand, SIG5 is induced by various stresses and contributes to repair of damaged photosystem II (PSII) through transcription of the psbD and psbC genes. Thus target genes and the physiological role of each sigma subunit are becoming clearer.
    Download PDF (281K)
Analytical Chemistry Regular Paper
  • Peter ROOS, Åsa WESTLING, Ioannis S. CHRONAKIS
    2004 Volume 68 Issue 11 Pages 2247-2256
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Cationic starch, cationic cellulose derivatives, and hydrophobically modified cationic cellulose were physically adsorbed from aqueous solution onto oppositely charged hydrophobic polyester (poly(ethylene terephthalate)) fabric and nonwoven, and this resulted in hydrophilic surface properties. Surface coverage of the polysaccharides occurred primarily by strong electrostatic interactions, and the surface characteristics were evaluated by measuring the time required for a water droplet to be absorbed into the polyester material as well as by electron spectroscopy for chemical analysis (ESCA). From a comparison of the adsorption characteristics we assess the polysaccharide-dependent and substrate-dependent adsorption behavior and discuss the similarities and differences in the hydrophilic properties and wettability observed. In particular, the temperature of the cationic polysaccharide solutions in which the substrate was immersed, the configuration of the polymer in solution, and the presence of hydrophobic substituents on the cationic moiety have a considerable effect on the polysaccharide affinity and its adsorption on the surface, irrespective of the substrate type (fabric or nonwoven). We also evaluate the relative contribution of the polyelectrolyte molecular weight, concentration in solution, and degree of charge density along the polymer chain which determine the range of interactions and alter surface hydroplilicity dependent on the type of substrate.
    Download PDF (168K)
Organic Chemistry Regular Papers
  • Keun-Hong PARK, Mi-Hyun KIM, Sang-Hyug PARK, Hyun Jung LEE, In Kyu KIM ...
    2004 Volume 68 Issue 11 Pages 2224-2229
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Adhesion molecules composed of Gly–Arg–Gly–Asp–Ser (GRGDS) peptides and cell recognition ligands were inculcated into thermo-reversible hydrogel composed of N-isopropylacrylamide, with a small amount of succinyl poly(ethylene glycol) (PEG) acrylate (MW 3400) used as a biomimetic extracellular matrix (ECM). The GRGDS-containing p(NiPAAm-co-PEG) copolymer gel was studied in vitro for its ability to promote cell spreading and to increase the viability of cells by introducing PEG spacers. Hydrogel lacking the adhesion molecules proved to be a poor ECM for adhesion, permitting only a 20% spread of the seeded cells after 10 days. When PEG spacer arms, immobilized by a peptide linkage, had been integrated into the hydrogel, conjugation of RGD promoted cell spread by 600% in a 10-day trial. In addition, in a serum-free medium, only GRGDS peptides conjugated with the spacer arm were able to promote cell spread. In terms of the cell viability, GRGDS peptides conjugated with the PEG-carrying copolymer gel specifically mediated cell spread. This result supports the theory that specific recognition is the result of interaction between the integrin families on the fibroblast, and the RGD sequence on the p(NiPAAm-co-PEG) copolymer gel.
    Download PDF (116K)
  • Noritaka IWAI, Takuma EBATA, Hirokatsu NAGURA, Tomoya KITAZUME, Kazuo ...
    2004 Volume 68 Issue 11 Pages 2265-2269
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    We have previously reported that a novel S-benzylisothiourea derivative, S-(3,4-dichlorobenzyl)isothiourea, tentatively named A22, induced spherical cells in Escherichia coli. To elucidate the structural element(s) required for inducing these spherical cells, the biological activity of S-benzylisothiourea derivatives and related compounds toward E. coli cells was investigated. S-(4-Chlorobenzyl)isothiourea revealed spherical cell-inducing activity, although being slightly less potent than A22, and S-benzylisothiourea itself showed much less activity. S-Cyclohexylmethylisothiourea did not show antibacterial activity and had little effect on the cell shape. S-Heptylisothiourea showed antibacterial activity and induced elongated cells rather than spherical cells. Benzylisothiocyanate inhibited cell growth but did not induce spherical cells. S-Ethylisothiourea, benzylthiocyanate, benzylisocyanate, and N-phenylthiourea did not show any activity under the present experimental conditions. These results indicate that the S-benzylisothiourea structure was necessary and sufficient for inducing spherical cells and that 3- and/or 4-chloro-substitution of the S-benzyl group enhanced this activity.
    Download PDF (140K)
  • Masahiro OKADA, Isao SATO, Soo Jeong CHO, Yoshihiro SUZUKI, Makoto OJI ...
    2004 Volume 68 Issue 11 Pages 2374-2387
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Bacteria produce and respond to signal molecules depending on their cell density. This process is called “quorum sensing”. The ComX pheromone, controlled by quorum sensing, activates natural genetic competence in Bacillus subtilis. ComX is an oligopeptide with a posttranslational modification. It has been suggested that ComX pheromone is modified with an isoprenoid at its tryptophan residue, but the complete chemical structure is unknown. We first determined the molecular formula of ComXRO-E-2, a competence factor for B. subtilis strain RO-E-2. Then we synthesized putative pheromones with 1-, 2-, 4-, 5-, 6-, or 7-geranyl substituted tryptophan residues. The regio- and stereo-selective synthesis of the geranyl tryptophans was successful, and we prepared the six peptides with modified tryptophan residues. These peptides had the same molecular formula and showed similar hydrophobicity to the natural ComXRO-E-2 in LC–MS analysis. But, none of them showed the same retention time as the natural pheromone and none exhibited its biological activity. These results suggest that the isoprenoid modification pattern of the tryptophan residue is more complex than postulated.
    Download PDF (226K)
Organic Chemistry Notes
Biochemistry & Molecular Biology Regular Papers
  • Chang Long AN, Woo Jin LIM, Su Young HONG, Eun Ju KIM, Eun Chule SHIN, ...
    2004 Volume 68 Issue 11 Pages 2270-2278
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    A putative bgl operon of Pectobacterium carotovorum subsp. carotovorum LY34 (Pcc LY34) was isolated. Sequence analysis of the 5,557 bp cloned DNA fragment (accession no. AY542524) showed three open reading frames (bglT, bglP, and bglB) predicted to encode 287, 633, and 468 amino acid proteins respectively. BglT and BglP ORFs show high similarity to that of the Pectobacterium chrysanthemi ArbG antiterminator and ArbF permease respectively. Also, the latter contains most residues important for phosphotransferase activity. The amino acid sequence of BglB showed high similarity to various β-glucosidases and is a member of glycosyl hydrolase family 1. The purified BglB enzyme hydrolyzed salicin, arbutin, pNPG, and MUG. The molecular weight of the enzyme was estimated to be 53,000 Da by SDS–PAGE. The purified β-glucosidase exhibited maximal activity at pH 7.0 and 40 °C, and its activity was enhanced in the presence of Mg2+. Two glutamate residues (Glu173 and Glu362) were found to be essential for enzyme activity.
    Download PDF (168K)
  • Qianghua XU, Yoshinori KATAKURA, Makiko YAMASHITA, Shengguo FANG, Taka ...
    2004 Volume 68 Issue 11 Pages 2279-2284
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    An in vitro immunization (IVI) protocol enables antigen specific antibody production from L-Leucyl-L-Leucine methyl ester (LLME)-treated human peripheral blood lymphocytes (PBL) upon antigen stimulation in the presence of IL-2, IL-4, and muramyl dipeptide. In the course of our studies, we have found that IL-10 added at the antigen sensitization significantly augmented antibody production level from the LLME-treated PBL. In the present study, we tried to demonstrate the role of IL-10 in the augmentation of antibody production in an IVI protocol by clarifying the cytokine expression profiles in CD4+ and CD8+ T cells. The results showed that IL-10 skewed the Th1/Th2 balance to Th2-type responses by suppressing Th1-type cytokine production and augmenting Th2-type cytokine production in CD4+ and CD8+ T cells, as well as in CD19+ B cells. Furthermore, IL-10 augmented the expression of CD38, an antigen marker of plasma cells, on B cells, which clearly indicates that IL-10 promoted differentiation and maturation of B cells in an IVI protocol. These results indicate that IL-10 plays an important role in setting the cellular milieu to produce antibodies in an IVI protocol.
    Download PDF (244K)
  • Seonghun KIM, Sun Bok LEE
    2004 Volume 68 Issue 11 Pages 2289-2298
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Homolog to lipolytic enzymes having the consensus sequence Gly–X–Ser–X–Gly, from the Sulfolobus solfataricus P2 genome, were identified by multiple sequence alignments. Among three potential candidate sequences, one (Est3), which displayed higher activity than the other enzymes on the indicate plates, was characterized. The gene (est 3) was expressed in Escherichia coli, and the recombinant protein (Est3) was purified by chromatographic separation. The enzyme is a trimeric protein and has a molecular weight of 32 kDa in monomer form in its native structure. The optimal pH and temperature of the esterase were 7.4 and 80 °C respectively. The enzyme showed broad substrate specificities toward various p-nitrophenyl esters ranging from C2 to C16. The catalytic activity of the Est3 esterase was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF) and diethyl p-nitrophenyl phosphate. Based on substrate specificity and the action of inhibitors, the Est3 enzyme was estimated to be a carboxylesterase (EC 3.1.1.1). The enzyme with methyl (±)-2-(3-benzoylphenyl)propionate-hydrolyzing activity to (−)-2-(3-benzoylphenyl)propionic acid displayed a moderate degree of enantioselectivity. The product, (−)-2-(3-benzoylphenyl)propionic acid, rather than its methyl ester, was obtained in 80% enantiomeric excess (e.e.p) at 20% conversion at 60 °C after a 32-h reaction. This result indicates that S. solfataricus esterase can be used for application in the synthesis of chiral compounds.
    Download PDF (209K)
  • Atsushi SHIMONAKA, Yuko BABA, Jinichiro KOGA, Akitaka NAKANE, Hidetosh ...
    2004 Volume 68 Issue 11 Pages 2299-2305
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    We previously cloned three endoglucanase genes, rce1, rce2, and rce3, from Rhizopus oryzae as the first cellulase genes from the subdivision Zygomycota. In this study, an endoglucanase gene, designated a pce1 gene, was cloned by plaque hybridization with the codon usage-optimized rce1 gene as a probe from Phycomyces nitens, a member of the subdivision Zygomycota. The pec1 gene had an open reading frame of 1,038 nucleotides encoding an endoglucanase (PCE1) of 346 amino acid residues. The amino acid sequence deduced from the pce1 gene consisted of a cellulose-binding domain (CBD) at the N terminus and of a catalytic domain belonging to family 45 glycoside hydrolase at the C terminus. PCE1 was purified to apparent homogeneity from the culture supernatant of P. nitens and the molecular mass was found to be 45 kDa. The optimum pH for the CMCase activity of PCE1 was 6.0, and the optimum temperature was 50 °C, the lowest among the family 45 endoglucanases.
    Download PDF (169K)
  • Takahiro OKADA, Iwona K. WOWER, Jacek WOWER, Christian W. ZWIEB, Makot ...
    2004 Volume 68 Issue 11 Pages 2319-2325
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Escherichia coli ribosomal protein S1 is composed of six repeating homologous oligonucleotide/oligosaccharide-binding fold (OB folds). In trans-translation, S1 plays a role in delivering transfer-messenger RNA (tmRNA) to stalled ribosomes. The second OB fold of S1 was found to be protected from tryptic digestion in the presence of tmRNA. Truncated S1 mutant Δ2, in which the first and second OB folds were deleted, showed significantly decreased tmRNA-binding activity. Furthermore, the E. coli S1 homolog (BS1) from Bacillus subtilis, which corresponds to the four C-terminal OB folds of E. coli S1, showed no interaction with E. coli tmRNA, as judged by the results of a gel shift assay. Surface plasmon resonance analysis revealed that mutant Δ2 and BS1 had decreased association rate constants (ka, 0.59×103 M−1·S−1; and ka, 1.89×103 M−1·S−1), while they retained the respective dissociation rate constants (kd, 0.67×10−3 S−1; and kd, 0.53×10−3 S−1), in comparison with wild-type protein S1 (ka, 3.32×103 M−1·S−1; and kd, 0.56×10−3 S−1). These results suggest that the second OB fold in protein S1 is essential for the recognition of tmRNA, while the four C-terminal OB folds play a role in stabilizing the S1–tmRNA complex.
    Download PDF (257K)
  • Masaki KUBOTA, Masahisa TSUJI, Mamoru NISHIMOTO, Jintanart WONGCHAWALI ...
    2004 Volume 68 Issue 11 Pages 2346-2352
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Three kinds of α-glucosidases, I, II, and III, were purified from European honeybees, Apis mellifera L. In addition, an α-glucosidase was also purified from honey. Some properties, including the substrate specificity of honey α-glucosidase, were almost the same as those of α-glucosidase III. Specific antisera against the α-glucosidases were prepared to examine the localization of α-glucosidases in the organs of honeybees. It was immunologically confirmed for the first time that α-glucosidase I was present in ventriculus, and α-glucosidase II, in ventriculus and haemolymph. α-Glucosidase III, which became apparent to be honey α-glucosidase, was present in the hypopharyngeal gland, from which the enzyme may be secreted into nectar gathered by honeybees. Honey may be finally made up through the process whereby sucrose in nectar, in which glucose and fructose also are naturally contained, is hydrolyzed by secreted α-glucosidase III.
    Download PDF (237K)
  • Dararat MEKKRIENGKRAI, Tomoki SANDO, Kazutake HIROOKA, Jitladda SAKDAP ...
    2004 Volume 68 Issue 11 Pages 2360-2368
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Farnesyl diphosphate is involved in rubber biosynthesis as an initiating substrate for both polyprenol and mushroom rubber. So far, we have isolated the cDNA of a farnesyl diphosphate synthase (FPS) for the first time from a rare rubber-producing mushroom, Lactarius chrysorrheus, by the degenerate RT-PCR technique based on sequence information of FPS genes from fungi and yeasts. The open reading frame was clarified to encode a protein of 381 amino acid residues with a calculated molecular weight of 42.9 kDa. The deduced amino acid sequence of L. chrysorrheus FPS showed about 50% identity with those of other fungi and yeasts as well as plants. We expressed the cDNA of L. chrysorrheus FPS in Escherichia coli as a glutathione-S-transferase (GST)-fusion protein. The purified obtained protein showed FPS activity in which geranyl diphosphate (GPP) served as primary substrate, with a 2.4-fold higher kcatKm value for GPP than for dimethylallyl diphosphate (DMAPP).
    Download PDF (231K)
  • Masahiro NAKAJIMA, Hiromi IMAMURA, Hirofumi SHOUN, Sueharu HORINOUCHI, ...
    2004 Volume 68 Issue 11 Pages 2369-2373
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Amylase A from Dictyoglomus thermophilum is a thermophilic enzyme and has about 40% identity with 4-α-glucanotransferase (GTase) from Thermococcus litoralis, and both of these enzymes belong to family 57 glycosyl hydrolase. Since the transglycosylation activity of T. litoralis GTase has been well characterized, the substrate specificity and reaction products of amylase A from D. thermophilum were examined. α-1,4 Glucan was produced from maltooligosaccharides, and glucoamylase-resistant molecules (cycloamyloses) were produced from longer chain amylose (average molecular mass 200 kDa). It has been reported that amylase A from D. thermophilum hydrolyzes starch, but in this study it was found that the enzyme was also able to use maltooligosaccharides and long chain amylose as substrate and has transglycosylation activity.
    Download PDF (135K)
Biochemistry & Molecular Biology Notes
Food & Nutrition Science Regular Papers
  • Asako NARAI, Hirohito WATANABE, Toshihiko IWANAGA, Toshio TOMITA, Mako ...
    2004 Volume 68 Issue 11 Pages 2230-2238
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    We have previously found a transepithelial electrical resistance (TEER)-decreasing protein derived from Flammulina velutipes, which was revealed to be identical to flammutoxin (FTX) that is known as a hemolytic pore-forming protein. This protein induced a rapid decrease in TEER and parallel increase in paracellular permeability in the intestinal epithelial Caco-2 cell monolayer without any cytotoxicity. An immunoblotting analysis revealed that the FTX-induced decrease in TEER was accompanied by the formation of a high-molecular-weight complex on the surface of Caco-2 cells. Intracellular Ca2+ imaging showed that exposure to FTX caused a rapid Ca2+ influx. It was observed by electron microscopy that FTX induced swelling of microvilli and expansion of the cellular surface. Staining with fluorescent phalloidin showed a marked change to filamentous actin in the FTX-treated cells.
    These results suggest that TEER reduction could sensitively detect small membrane pore formation by FTX in the intestinal epithelium which causes a morphological alteration and disruption of the paracellular barrier function.
    Download PDF (327K)
  • Toshiro MATSUI, Sumi EBUCHI, Keiichi FUKUI, Kazusato MATSUGANO, Norihi ...
    2004 Volume 68 Issue 11 Pages 2239-2246
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    The suppressive effect on the postprandial blood glucose rise through α-glucosidase (AGH) inhibition was investigated in this study in order to clarify an antihyperglycemic function of 6-O-caffeoylsophorose (CS) from diacylated anthocyanin. The administration of CS (100 mg/kg) following maltose (2 g/kg) to Sprague-Dawley rats resulted in the maximal blood glucose level after 30 min being significantly decreased by 11.1% compared to the control. A reduction in the serum insulin secretion was also observed in parallel to the decrease in blood glucose level. No blood glucose change was apparent when sucrose or glucose was ingested, suggesting that the antihyperglycemic effect of CS was achieved by maltase inhibition, rather than by sucrase or glucose transport inhibition. An AGH inhibitory assay demonstrated that the non-competitive maltase inhibition of CS was partly due to acylation by phenolic acid with sugar, the presence of hydroxyl groups in the aromatic ring, and the presence of an unsaturated alkyl chain in the acylated moiety.
    Download PDF (148K)
  • Soo Bong CHOI, Chun Hee PARK, Mi Kyung CHOI, Dong Wha JUN, Sunmin PARK
    2004 Volume 68 Issue 11 Pages 2257-2264
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    The effect of supplementation with Phellinus linteus (P. linteus), Paecilomyces tenuipes (P. tenuipes), and Cordyceps militaris (C. militaris) mushroom water extracts on the insulin secretion and insulin resistance of 90% pancreatectomized (Px) male Sprague Dawley rats was investigated. Px rats were daily administered 0.5 g of P. linteus, P. tenuipes, and C. militaris aqueous extracts or a placebo per 1 kg body weight with a 40% fat diet for 8 weeks. Fasting serum glucose levels were lower in rats receiving C. militaris than in the control group. Insulin secretion at the elevated serum glucose levels was lowest in rats that consumed P. tenuipes in hyperglycemic clamp. Whole body glucose disposal rates increased in C. militaris but decreased in P. tenuipes compared to those in the control group in euglycemic hyperinsulinemic clamp. The GLUT4 content and fraction velocity of glycogen synthase in the soleus and quadriceps muscles increased in the rats treated with C. militaris, but P. tenuipes decreased both. In sum, a water extract of C. militaris ameliorates insulin resistance by enhancing glucose utilization in skeletal muscles.
    Download PDF (107K)
  • Kiyoshi KAWAI, Tomoaki HAGIWARA, Rikuo TAKAI, Toru SUZUKI
    2004 Volume 68 Issue 11 Pages 2285-2288
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    The Maillard Reaction (MR) rate below the glass transition temperature (Tg) for various model glassy food systems was studied at temperatures between 40 °C and 70 °C. As a sample, freeze-dried glucose and lysine systems embedded in various glassy matrices (e.g., polyvinylpyrrolodone and trehalose) were used, and the MR rate below the Tg was compared among the various glassy matrices. The extent of MR was estimated spectrophotometrically from the optical density at 280 nm (OD280), and the MR rate (k280) was determined as a pseudo zero order reaction rate from the time course of OD280. Although k280 was described by the Arrhenius plot, the temperature dependence of k280 was almost the same and the intercept was different among the matrices. From the comparison of k280, it was suggested that the MR rate in glassy matrix was affected not only by the Tg, but also by the hydrogen bonding between MR reactants and glassy matrix.
    Download PDF (91K)
  • Xu WEN, Makiko TAKENAKA, Masatsune MURATA, Seiichi HOMMA
    2004 Volume 68 Issue 11 Pages 2313-2318
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Coffee brew contains a brownish zinc-chelating polymer designated ApV. ApV was prepared from the precipitate formed in a solution of instant coffee by adding ZnCl2 and purified using ion-exchange and cellulose column chromatographies. The antioxidative activities of ApV and related compounds were evaluated in this study. The free-radical scavenging activity of ApV estimated by ABTS assay was at a similar level to that of instant coffee, while the O2 scavenging activity of ApV, which is superoxide dismutase-like activity, was lower than that of instant coffee. The hydroxyl-radical scavenging activity of ApV was higher than that of instant coffee, and the auto-oxidation of linoleic acid was more strongly inhibited by ApV than by caffeic acid.
    Download PDF (99K)
  • Kazuki NAKASHIMA, Shigehiko MASAKI, Makoto YAMAZAKI, Hiroyuki ABE
    2004 Volume 68 Issue 11 Pages 2326-2331
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    The effects of cysteine as an antioxidant nutrient on change in protein modification and myofibrillar proteolysis in chick myotubes by induction of oxidative stress by H2O2 treatment were investigated. Myotubes were treated for 1 h with H2O2 (1 mM). After this treatment, the H2O2 was removed and the cells were cultured in cysteine (0.1 and 1 mM) containing serum-free medium for 24 h. Protein carbonyl content as an index of protein modification and Nτ-methylhistidine release as an index of myofibrillar proteolysis were increased at 24 h after H2O2 treatment, and the increment was reduced by cysteine. Calpain, proteasome and cathepsin (B+L and D) activities were increased at 24 h after H2O2 treatment, and the increment was also reduced by cysteine. These results indicate that cysteine suppresses protein modification by oxidative stress, resulting in a decrease of protease acitivities, finally resulting in a decrease in myofibrillar proteolysis in chick myotubes.
    Download PDF (100K)
  • Kazuo RYOYAMA, Yumi KIDACHI, Hideaki YAMAGUCHI, Hideki KAJIURA, Hiroki ...
    2004 Volume 68 Issue 11 Pages 2332-2340
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Oral administration of an enzymatically synthesized α-1,4:1,6-glycogen (ESG) at a dose of 50 μg/ml significantly prolonged the survival time of Meth A tumor-bearing mice. ESG also significantly stimulated macrophage-like cells (J774.1), leading to augmented production of nitric oxide (NO) and tumor necrosis factor-α (TNF-α). The weight-average degree of polymerization (DPw) and the ratio of branch linkage (BL) of ESG were 149,000 and 8.1% respectively. β-Amylase-treated ESG, however, lost J774.1-activating activity although inhibited subcutaneous growth of Meth A tumor cells admixed with it. Its DPw and BL changed to 126,000 and 20% respectively. Partially degraded amylopectin [(AP), DPw: 110,000, BL; 5.1] was also effective at stimulating J774.1, but its activity was lower than that of ESG. Other α-glucans [cycloamylose (CA), enzymatically synthesized amylose (ESA), highly branched cyclic dextrin (HBCD), and β-amylase-treated HBCD], of which DPw was lower than that of ESG, showed no J774.1-activating activity and weaker anti-tumor activity.
    Download PDF (124K)
  • Takashi FURUYASHIKI, Hironobu NAGAYASU, Yukiko AOKI, Hiroaki BESSHO, T ...
    2004 Volume 68 Issue 11 Pages 2353-2359
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Obesity is a serious health problem, and its prevention is promoted through life style including diet and exercise. In this study, we investigated the suppressive effects of tea catechin on the differentiation of 3T3-L1 preadipocytes to adipocytes. (−)-Catechin 3-gallate (CG), (−)-epigallocatechin (EGC), (−)-epicatechin 3-gallate, and (−)-epigallocatechin 3-gallate at 5 μM suppressed intracellular lipid accumulation. The suppressive effects of CG and EGC were stronger than the others, and CG and EGC also suppressed the activity of glycerol-3-phosphate dehydrogenase as a differentiation marker. These catechins inhibited the expression of peroxisome proliferator-activated receptor (PPAR) γ2 and CCAAT/enhancer-binding protein (C/EBP) α, both of which act as key transcription factors at an early stage of differentiation, followed by the expression of glucose transporter (GLUT) 4 at a later stage. In addition, the catechins did not affect the phosphorylation status of the insulin signal pathway. Thus, catechin suppressed adipocyte differentiation accompanied by the down-regulation of PPARγ2, C/EBPα, and GLUT4. These results suggest that tea catechin prevents obesity through the suppression of adipocyte differentiation.
    Download PDF (158K)
Food & Nutrition Science Notes
Microbiology & Fermentation Technology Regular Papers
  • Kohji ISHIHARA, Hiroaki YAMAMOTO, Kazuya MITSUHASHI, Kazuyoshi NISHIKA ...
    2004 Volume 68 Issue 11 Pages 2306-2312
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    An NADPH-dependent α-keto amide reductase was purified from Saccharomyces cerevisiae. The molecular mass of the native enzyme was estimated to be 33 and 36 kDa by gel filtration chromatography and SDS–polyacrylamide gel electrophoresis, respectively. The purified enzyme showed a reducing activity not only for aromatic α-keto amides but also for aliphatic and aromatic α-keto esters. The internal sequence of the enzyme was identical with that of a hypothetical protein (ORF YDL 124w) coded by yeast chromosome IV.
    Download PDF (153K)
  • Hiroshi KANZAKI, Satohiro YANAGISAWA, Teruhiko NITODA
    2004 Volume 68 Issue 11 Pages 2341-2345
    Published: 2004
    Released: November 23, 2004
    JOURNALS FREE ACCESS
    Cyclo(His–Phe) was effectively converted to its dehydro derivatives by the enzyme of Streptomyces albulus KO-23, an albonoursin-producing actinomycete. Two types of dehydro derivatives were isolated from the reaction mixture and identified as cyclo(ΔHis–ΔPhe) and cyclo(His–ΔPhe). This is the first report on cyclo(His–ΔPhe) and the enzymatic preparation of both compounds. Cyclo(ΔHis–ΔPhe), a tetradehydro cyclic dipeptide, exhibited a minimum inhibitory concentration of 0.78 μmol/ml inhibitory activity toward the first cleavage of sea urchin embryos, in contrast to cyclo(His–ΔPhe) that had no activity. The finding that the isoprenylated derivative of cyclo(ΔHis–ΔPhe), dehydrophyenylahistin, had 2,000 times higher activity than cyclo(ΔHis–ΔPhe) indicates that an isoprenyl group attached to an imidazole ring of the compound was essential for the inhibitory activity.
    Download PDF (82K)
feedback
Top