Telomeres are protected and maintained by telomere-specific proteins. In addition, proteins involved in DNA repair, such as Mre11-Rad50-Nbs1 complex, RPA, and RecQ helicase, are also involved in telomere maintenance. In this review, the roles of these proteins in telomere maintenance and their functional relationships to the telomere-specific proteins will be discussed.
Post-transcriptional regulation as well as transcriptional regulation plays an important role in the expression of genes under stressed conditions in Saccharomyces cerevisiae. Under stressed conditions caused by heat shock or ethanol, yeast cells alter not only their transcriptional patterns but also the types of mRNA to be exported from the nucleus in order to adapt rapidly to the stress. Under heat-shocked conditions at 42 °C, bulk poly (A)+ mRNA accumulates in the nucleus, whereas stress-induced transcripts such as HSP mRNAs are efficiently exported. Ethanol stress also causes nuclear accumulation of bulk poly (A)+ mRNA, but elicits a different response regarding the transport of HSP mRNAs. Other differences between the heat shock response and the ethanol stress response were observed in the nuclear processing of transcripts and in cytosolic mRNA flux. This review outlines the regulation of yeast gene expression at the mRNA processing and nuclear export steps under ethanol stressed conditions, and discusses how to improve the capabilities of brewer’s yeast cells.
Natural polyisoprene is a biopolymer consisting of isoprene units (C5H8) that is used commercially in household, medical, and industrial materials. For the management of natural polyisoprene production, the selection of high-yield polyisoprene-producing trees, and an understanding of polyisoprene biosynthesis, a high-throughput and highly sensitive screening method for the quantification of polyisoprene is required. In this study, we examined pyrolysates from polyisoprenes, polyprenols, carotenoids, ubiquinone (CoQ-10), and sterols by pyrolysis gas chromatography/mass spectrometry (PyGC/MS) and determined that the amounts of isoprene and limonene released from polyprenols and polyisoprenes were dependent upon their molecular weights. Based on these results, we developed a relative quantification method for polyisoprene in leaves by direct analysis of 1 mg of leaves using PyGC/MS. This novel quantification method eliminated extraction steps and can be used in the measurement of polyisoprene contents in Eucommia ulmoides and Hevea brasiliensis.
Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce a novel sex pheromone composed of three methyl-branched ketones: 6-methyl-2-octadecanone (I), 14-methyl-2-octadecanone (II), and 6,14-dimethyl-2-octadecanone (III). Their structures were confirmed by syntheses accomplished by a different route for each component. In order to obtain a sufficient amount of the synthetic pheromone, we developed new routes via methyl-branched 1-alkenes: 6-methyl-1-octadecene (1), 14-methyl-1-octadecene (2), and 6,14-dimethyl-1-octadecene (3). Compound 1 was synthesized by coupling between a C10-chain bromide and a 3-methyl-branched C8 unit (A) prepared from 3-methyl-1,5-pentanediol, 2, by coupling between a C11-chain bromide and a 3-methyl-branched C7 unit (B) prepared from 2-hexanone, and 3, by connecting A and B, using propargyl alcohol as a C3 linchpin. The use of 3-chloro-1-propanol and tert-butyl acetoacetate as the linchpin was also examined to connect the two synthetic blocks in the synthesis of 3. Components I–III were obtained by Wacker oxidation of the corresponding 1-alkenes 1–3 in good yields.
A powerful inhibitor of TNF-α production, vialinin A, was synthesized from sesamol through a series of reactions involving double Suzuki-Miyaura coupling, 2,3-dichloro-5,6-dicyano-1,4-benzoquino (DDQ) mediated de-methoxymethylation and oxidative removal of methylene acetal by lead tetraacetate. The synthetic method also made it possible to prepare a related compound, terrestrin B.
A search for C35-terpenes from non-saponified extracts of 12 non-pathogenic Mycobacterium species was carried out. Octahydroheptaprenyl mycolic acyl esters were isolated from M. chlorophenolicum cells which were also found from M. thermoresistibile, M. vanbaalenii, M. aichiense, M. smegmatis, and M. parafortuitum. This is the first report on a polyprenol esterified by a mycolate. A novel monocyclic C35-terpene possessing a ketone, named heptaprenylcycline B, was isolated, which was detected from M. chlorophenolicum and M. vanbaalenii. The biosynthetic pathway to heptaprenylcycline B was investigated with ancymidol which acts as an inhibitor of a P450 monooxygenase. This experiment suggested that the P450 monooxygenase may be responsible for the production of heptaprenylcycline B.
A new enantioselective total synthesis of pachastrissamine (jaspine B) was achieved from a known α,β-unsaturated aldehyde by utilizing Córdova’s asymmetric epoxidation as the chirality-inducing step. The 2,3-cis stereochemistry of pachastrissamine was established via intramolecular epoxide ring opening of a γ,δ-epoxy-α,β-unsaturated ester intermediate coupled with oxy-Michael cyclization. Treatment of pachastrissamine with tetrahydro-2-furanol under acidic conditions led to smooth oxazolidine ring formation, furnishing jaspine A in a high yield.
Potent inhibitory activity of the leaves of Myrica rubra against both chemical and enzymatic (tyrosinase and lipoxygenase) oxidation was found in our project to develop utility of unused and rarely used plant resources in the local area. A constituent analysis of the most active ethyl acetate-soluble part of a methanol extract of the leaves clarified the structures of eight major compounds. The tyrosinase and lipoxygenase inhibitory activities and DPPH radical scavenging activity of the isolated compounds were measured as indicators of the inhibitory capacity against the enzymatic and chemical oxidation of food. The obtained data indicate that the chemical and enzymatic (lipoxygenase and tyrosinase) antioxidant activities of the leaves mainly depended on the galloyl flavonoid derivatives.
The retarding activity of 6-O-dodecanoyl-D-allose against rice growth was higher than that of the octanoate and the decanoate. The activities of 6-O-dodecanoyl-D-glucose, -D-mannose, and -D-galactose against rice seedlings were examined. 6-O-Dodecanoyl-D-allose exhibited the highest activity, suggesting the importance of the α-axial hydroxy group at C-3 of D-allose.
In Bacillus subtilis, the germination-related lipase LipC is located in the spore coat, and mutant spores are defective in L-alanine-stimulated germination. To determine the physiological role of LipC, the recombinant LipC expressed in Escherichia coli was purified and characterized. The enzyme hydrolyzes p-nitrophenyl ester substrates with various acyl-chain lengths. Thin-layer chromatography and gas chromatography-mass spectrometry analysis indicated that LipC cleaves the fatty acids at the sn-1 and sn-2 positions of phospholipids as phospholipase B, and that the enzyme shows no selectivity for the polar head groups of lipid molecules. When the amounts of free fatty acids in dormant wild-type and lipC mutant (YCSKd) spores were measured, the amount of free fatty acids in the YCSKd spores was about 35% less than in the wild-type spores. These results suggest the possibility that Bacillus subtilis LipC plays an important role in the degradation of the outer spore membrane during sporulation.
The aryl hydrocarbon receptor (AhR) is a transcription factor that is activated by dioxin and related xenobiotics. Although the activation of AhR is inhibited by tyrosine kinase inhibitors, the molecular mechanism has not been clarified. In the current study, the inhibitory mechanisms of several inhibitors of tyrosine kinase, herbimycin A, genistein, and tyrphostin B48, on AhR activation was analyzed in human Caco-2 cells. All the inhibitors suppressed the transcriptional activation of AhR induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Herbimycin A induced down-regulation of the AhR protein by inhibiting its molecular chaperone heat shock protein 90 (HSP90). In contrast, genistein and tyrphostin B48 inhibited the nuclear localization of AhR induced by TCDD, although the amount of AhR protein was not altered. The inhibitory effects of genistein and tyrphostin B48 on endogenous tyrosine kinase activity were evaluated by detection of alterations in the tyrosine phosphorylation states of cellular proteins.
The C-type natriuretic peptide/natriuretic peptide receptor-B/cGMP pathway plays an important role in the regulation of endochondral ossification. In chondrocytes, the physiological effect of cGMP is mediated primarily by the activation of cGMP-dependent protein kinase II (cGK-II). In this study, we investigated the transcriptional regulation of cGK-II in chondrocytes. The expression pattern of cGK-II transcripts was examined during chondrogenic differentiation of ATDC5 cells. cGK-II mRNA was not detectable in undifferentiated cells, but increased dramatically prior to differentiation to the hypertrophic stage. To analyze the transcriptional regulation of cGK-II, the 5′-flanking region of the mouse cGK-II gene was isolated and characterized. The promoter activity of the cGK-II gene decreased markedly following deletion and mutagenesis of the putative Nkx-binding site between nucleotide positions −292 and −286. These results suggest that the homeobox gene Nkx family is critical for the transcriptional regulation of cGK-II during chondrogenesis.
The crystal structure of a cold-active alkaline phosphatase from a psychrophile, Shewanella sp. (SCAP), was solved at 2.2 Å. A refined model showed a homodimer with six metal-ligand sites. The arrangement of the catalytic residues resembled those of alkaline phosphatases (APs), suggesting that the reaction mechanism of SCAP was fundamentally identical to those of other APs. SCAP had two distinct structural features: (i) a loop with Arg122 that bound to the phosphate moiety of the substrate suffered no constraints from the linkage to other secondary structures, and (ii) Mg3-ligand His109 was considered to undergo repulsive effect with neighboring Trp228. The local flexibility led by these features might be an important factor in the high catalytic efficiency of SCAP at low temperatures.
Mutations in Troponin I (TnI) and Troponin T (TnT) are closely linked to familial hypertrophic cardiomyopathy (FHC) and hypertrophic cardiomyopathy (HCM), but the underlying molecular mechanism is not yet well understood. There might be a close link between the defective dynamic properties and the functional aberrations of hcTroponin. To prove this hypothesis, we undertook detailed NMR relaxation measurements of [2H, 13C, 15N] labeled proteins reconstituted into hcTroponin in both the Ca2+- and the Mg2+-loaded state. The wild-type TnI and two FHC causing mutations, TnI(G203S) and TnI(ΔK183), were investigated. To ensure that defective dynamic properties are not only a particular feature for mutations in the flexible part of TnI, measurements of the TnT mutation TnT(R278P) were also performed. For all mutations significant dynamic changes in the area for Troponin C (TnC) and actin-Tm binding were obtained. These measurements provide important information to understand the functional aberrations of FHC and HCM causing mutation in human cardiac Troponin (hcTn).
A novel protein, Smsp-72k, was found to be selectively expressed in the silk gland of aquatic larvae of the Stenopsychid caddisfly (Stenopsyche marmorata). The protein was characterized by an abundance of cysteine (13.97%) and charged residues (47.21%). Amino acids with hydroxyl side-chains accounted for an additional 10% of the Smsp-72k protein, with serine at 4.4% and threonine at 5.6%. A cysteine-rich repetitive sequence is common to many potential and known underwater adhesive/cement proteins and cell-cell adhesion molecules. We hypothesized that Smsp-72k is an adhesive/cement protein that increases the adhesiveness of the silk fiber of S. marmorata. The hydroxyl groups of Smsp-72k might form a link with the heavy chain fibroin of S. marmorata, removing the weak boundary-water layer and allowing the spreading of the silk protein onto the surface of the substratum during the process of adhesion.
A novel enzyme that catalyzes the efficient hydrolysis of Glu-Glu was isolated from soybean cotyledons by ammonium sulfate fractionation and successive column chromatographies of Q-sepharose, Phenyl sepharose, and Superdex 200. The apparent molecular mass of this enzyme was found to be 56 kDa and 510 kDa by SDS-polyacrylamide gel electrophoresis and Superdex 200 HR 10/30 column chromatography respectively. The enzyme had high activity against Glu-p-nitroanilide (pNA) and Asp-pNA, whereas Leu-pNA, Phe-pNA, Ala-pNA, and Pro-pNA were not hydrolyzed. The synthetic dipeptides Glu-Xxx and Asp-Xxx were hydrolyzed, but Xxx-Glu was not. The digestion of a Glu-rich oligopeptide, chromogranin A (Glu-Glu-Glu-Glu-Glu-Met-Ala-Val-Val-Pro-Gln-Gly-Leu-Phe-Arg-Gly-NH2) using this purified enzyme was also investigated. Glutamic acid residues were cleaved one by one from the N-terminus. These observations indicate that the enzyme removes glutamyl or aspartyl residues from N-terminal acidic amino acid-containing peptides. It is thought that it was an N-terminal acidic amino acid-specific aminopeptidase from a plant.
Fyn-related kinase (Frk) was first identified using human breast cancer cells. It shares 51% identity with c-Src. Like all members of the Src family, Frk is thought to cause several cancers via dysregulations in signal transduction from cell-surface receptors. The excess activity of Frk on β-cells has a crucial role in type-I diabetes. A silent mutation at Ile229 conferred a bacterial expression system on the kinase domains of Frk, which allowed for the quick expression and purification of one unphosphorylated and two mono-phosphorylated kinase domains. The C-terminal catalytic segment of the human Frk kinase conjugating hexahistidine purification tag (His-tag) was expressed in Escherichia coli. After first-step purification utilizing the His-tag, an anion-exchange chromatogram yielded three major peaks that had distinguishable phosphorylation characteristics as judged by Western blot analysis and measurement of kinase activity. This result of active protein production should promote drug discovery studies, including highthrough-put screening and structure-based drug design.
L-Amino acid ligase catalyzes dipeptide synthesis from unprotected L-amino acids in an ATP-dependent manner. We have purified a new L-amino acid ligase, RizA, which synthesizes dipeptides whose N-terminus is Arg, from Bacillus subtilis NBRC3134, a microorganism that produces a rhizocticin peptide antibiotic. It was suggested that RizA is probably involved in rhizocticin biosynthesis. In this study, we performed sequence analysis of unknown regions around rizA, and newly identified a gene that encodes a protein that possesses an ATP-grasp motif upstream of rizA. This gene was designated rizB, and its recombinant protein was prepared. Recombinant RizB synthesized homo-oligomers of branched-chain L-amino acids and L-methionine consisting of two to five amino acids in an ATP-dependent manner. RizB also synthesized various heteropeptides. Further examination showed that RizB might elongate a peptide chain at the N-terminus. This is the first report on an L-amino acid ligase catalyzing oligopeptide synthesis.
We disrupted the palH gene, which is known to participate in the ambient pH signal transduction pathway, in Aspergillus oryzae. palH disruption caused significant decreases in pacC expression and alkaline protease activity. Hence we believe that palH plays a very important role in controlling the alkaline protease level in A. oryzae.
Plants utilize UDP-arabinofuranose (UDP-Araf) in the biosynthesis of Araf-containing complex carbohydrates. UDP-Araf is synthesized from UDP-arabinopyranose by UDP-arabinopyranose mutases (UAMs). Here we describe the heterologous expression of rice (Oryza sativa) UAM genes in insect cells and report some of their enzymatic properties. Recombinant UAMs might serve as useful tools for the biosynthesis of UDP-Araf and might be better than chemical synthesis.
DNA replication without telomerase leads to telomere shortening and induces replicative senescence. We found that in a telomerase-deficient budding yeast mutant, the volume of each telomere-shortened cell increased as its growth capacity decreased, and that this process was associated with changes in vacuolar morphology. Senescence-induced cell expansion required Mec1, a DNA damage-responsive kinase, but not vacuolar SNARE Vam3.
Although cesium is known to be absorbed by plants, the pathway by which cesium enters has not been identified. We found that the AtKUP/HAK/KT9 gene from Arabidopsis thaliana was functionally expressed in a potassium transport-deficient Escherichia coli mutant. AtKUP/HAK/KT9 mediated potassium uptake as well as cesium transport. We found that AtKUP/HAK/KT9 might be involved in the pathway in questions.
A nuclease was purified from the fruit body of Tricholoma matsutake. The molecular mass was 38 kDa. The optimum pH of the nuclease was about 8.0. Its activity was inhibited by GTP. The nuclease cleaved RNA and heat-denatured DNA endonucleolytically to produce 5′-mononucleotide, and showed 3′-nucleotidase activity. The amino acid sequence up to seven amino acids from the N-terminus was NH2-APPPSSN.
Lacticin Q is an antimicrobial peptide that forms pores on membranes. We investigated effects of negatively charged lipids on the binding and pore formation of lacticin Q with liposomes by surface plasmon resonance analysis and fluorescence dye leakage experiments respectively. Negatively charged lipids accelerated the binding of lacticin Q on the membranes and the resulting pore formation. However, the acceleration was not an essential factor in the killing activity of lacticin Q, since pore-forming activities against electrically neutral and negatively charged liposomes occurred similarly.
We investigated the effects of oral intake of Lactobacillus helveticus-fermented milk whey on the intact and sodium dodecylsulfate (SDS)-exposed skin of Hos:HR-1 hairless mice. The mice were allowed to drink 10% L. helveticus-fermented milk whey in distilled water ad libitum for 5 weeks. SDS solution was topically applied to the dorsal skin at 4 weeks, leading to the development of dermatitis. The skin moisture content, transepidermal water loss, and sizes of the dermatitis areas were periodically measured. Compared with oral intake of water alone, oral intake of water containing L. helveticus-fermented milk whey for 4 weeks significantly lowered transepidermal water loss from intact skin, significantly reduced in size the areas of early SDS-induced dermatitis, and ameliorated both the SDS-induced decrease in moisture content and the increase in transepidermal water loss. These results suggest that oral intake of L. helveticus-fermented milk whey might be effective in promoting the epidermal barrier function and in preventing the onset of dermatitis.
Twelve essential oils were tested in vitro for antimicrobial activities against several strains of Campylobacter jejuni, a pathogen causing food-borne diseases worldwide. Using disk diffusion and minimal inhibitory concentration determination assays, we noted that coriander oil exhibited the strongest antimicrobial activity against all tested strains. The oil had a bactericidal effect on the target bacteria. In evaluating the antimicrobial potency of coriander oil against C. jejuni on beef and chicken meat at 4 °C and 32 °C, it was found that the oil reduced the bacterial cell load in a dose-dependent manner. The type of meat and temperature did not influence the antimicrobial activity of the oil. This study indicates the potential of coriander oil to serve as a natural antimicrobial compound against C. jejuni in food.
The objective of this study was to analyze human eating behaviors in chewing and slurping buckwheat noodles. We used electromyography to measure the activity of the jaw-closing, jaw-opening, and lip-closing muscles while healthy adults ate one mouthful of buckwheat noodles. Slurping the noodles required a longer mastication period but smaller muscle activity per movement than chewing the same samples. Total muscle activity was greater in slurping. Slurping also showed a longer average cycle time but greater variances in the cycle time than rhythmical chewing. The mechanical properties of buckwheat noodles significantly differed between the noodle types (half-raw and dry), but the human mastication variables for the two types of noodles were not significantly changed within a subject. Both types of noodles kept for 10 min at 23 °C after being cooked could be consumed with less mastication effort than those immediately served, and this observation corresponded to softening of the noodles during the standing time.
Polyphenols can oxidize in culture medium and produce artifacts in cell culture studies. However, the extent and mechanism of the oxidation of resveratrol, a polyphenol abundant in red wine, is unclear. We investigated the oxidation of resveratrol in vitro and the effects of various components of the culture medium on the degradation of resveratrol and the production of H2O2. We found that 96% of resveratrol at a concentration of 200 μM was degraded in Base Modified Eagle Medium after 24 h of incubation at 37 °C, producing about 90 μM of H2O2. Including sodium bicarbonate in the medium markedly stimulated resveratrol degradation and H2O2 production. In sum, we found that bicarbonate ions played a crucial role in the oxidative degradation of resveratrol in vitro, and that the degradation of resveratrol can be avoided by withdrawing sodium bicarbonate from the medium. A mechanism for the oxidation of resveratrol is proposed.
We have found that shochu distillery by-product (SDBP) contains a growth promoting factor that can be extracted with ether. In the present study, we administered hexane-extracts of SDBP (HSDBP) to broiler chickens and observed changes in skeletal muscle protein degradation in order to clarify the mechanism of growth promotion due to SDBP feeding. The pectoralis superficial muscle weight was significantly increased by HSDBP feeding. Plasma Nτ-methylhistidine concentration was significantly decreased by HSDBP, showing that the rate of muscle protein degradation decreased. It was also found that the expression of mRNA of ubiquitin-proteasome system and calpain was decreased by HSDBP. These results indicate that growth promotion due to SDBP is caused by suppression of skeletal muscle protein degradation, which is related to the ubiquitin-ptoteasome system and calpain.
The textural properties of cooked rice were investigated in the presence and the absence of gum arabic (GA) and soybean soluble polysaccharide (SSPS). SSPS was more effective in increasing the hardness and in decreasing the stickiness of the rice grains than GA. For both polysaccharides, the increase in hardness was more apparent in the whole body than at the periphery, whereas the decrease in stickiness was more apparent at the periphery than in the whole body. SSPS was more effective in retarding the gelatinization of rice starch and in lowering the elastic characters of the glutinous layer (the materials leached out of the rice grains during cooking) along with a decrease in the amount of amylopectin leached. The textural hardness of cooked rice was determined by the degree of starch gelatinization, whereas the textural stickiness was related to the rheological characters of the glutinous layer and the leaching profile of the starch components.
We examined the effects single and combined administration of fermented barley extract P (FBEP), prepared from barley-shochu distillery by-products, and γ-aminobutyric acid (GABA) on the development of atopic dermatitis (AD)-like skin lesions in NC/Nga mice. Single administration of FBEP and GABA dose-dependently reduced the development of AD-like skin lesions in mice. GABA reduced the development of AD-like skin lesions by suppressing serum immunoglobulin E (IgE) and splenocyte interleukin (IL)-4 production, while FBEP reduced skin lesions without affecting the IgE or cytokine production. However, in mice with induced AD-like skin lesions, combined administration of FBEP and GABA decreased serum IgE levels and splenic cell IL-4 production, and increased splenic cell interferon-γ production. These results suggest that combined administration of FBEP and GABA alleviated AD-like skin lesions in the NC/Nga mice by adjusting the Th1/Th2 balance to a Th1-predominant immune response.
The effects of dietary supplementation with methionine and cystine on lipid metabolism, including the serum lipid concentration, were studied in Donryu rats subcutaneously implanted with an ascites hepatoma cell line (AH109A) for comparison with normal rats. A diet supplemented with 1.2% L-methionine or L-cystine to 20% casein was found to suppress the hepatoma-induced increases in serum triglyceride and total cholesterol concentration. The lipoprotein lipase activity in tissues was enhanced by dietary methionine and cystine, with no change in the mRNA level. Dietary methionine and cystine increased bile acid excretion into the feces with enhanced hepatic cholesterol 7α-hydroxylase activity. Dietary methionine and cystine affected the lipid metabolism differently in normal rats from hepatoma-bearing rats. These results suggest that dietary methionine and cystine each had a hypolipidemic effect against cancer-induced hyperlipidemia, and that the different actions observed in the hepatoma-bearing and normal rats may have been due to a metabolic abnormality caused by the cancer.
γ-Tocopherol was reacted with (E)-4-oxo-2-nonenal (ONE) at 37 °C in an acidic acetonitrile solution. The reaction products were isolated by reversed-phase high-performance liquid chromatography and their structures were characterized to be 5-substituted γ-tocopherols: 5-(1-(furan-2-yl)pentyl)-γ-tocopherol (1), 3-(1-butyl-4,5,7-trimethyl-7-(4,8,12-trimethyltridecyl)-8,9-dihydro-7H-furo[3,2-f]chromen-2yl)propanal (2), and 1-(1-butyl-4,5,7-trimethyl-7-(4,8,12-trimethyltridecyl)-8,9-dihydro-7H-furo[3,2-f]chromen-2-yl)-4-(furan-2-yl)octan-3-one (3). Compound 1 was the predominant product under the mild acidic conditions, whereas compounds 2 and 3 were relatively stable and accumulated during the reaction. Compound 1 was detected as the product when γ-tocopherol and ONE were incubated in methyl linoleate in the presence of dicetyl phosphate. The results indicate that γ-tocopherol may trap ONE under acidic conditions of lipid peroxidation.
Coenzyme Q10 (CoQ10) is a popular food supplement. Earlier, we successfully produced CoQ10 in rice, which normally produces predominately CoQ9. Here we developed efficient production of CoQ10 in rice by introducing the gene for decaprenyl diphosphate synthase into rice sugary and shrunken mutants. These rices produced 1.3 to 1.6 times as much CoQ10 as the earlier enriched rice did.
Inosine monophosphate dehydrogenase (IMPDH), a rate-limiting enzyme in the de novo synthesis of guanine nucleotides, is a therapeutic target for anticancer and antiviral agents. Among the 15 different polyphenols examined, curcumin was found to have an inhibitory effect on the IMPDH activity in both a competitive and uncompetitive manner and to suppress the cellular GTP level in HT-29 colon carcinoma cells.
Tri a Bd 27K, a major wheat allergen, is a glycoprotein. Tri a Bd 27K was found to occur in multiple forms by two-dimensional polyacrylamide gel electrophoresis and immunoblotting with a monoclonal antibody against the allergen. Furthermore, it was found that only Tri a Bd 27K components, which have N-linked glycan moieties with fucose residues, bound to IgE antibodies in the sera of wheat-sensitive patients.
The effects were evaluated of various glycerophospholipids on the uptake of β-carotene solubilized in mixed micelles by human intestinal Caco-2 cells. Phosphatidylethanolamine markedly enhanced the transfer of β-carotene from the micelles to the cells, whereas phosphatidylcholine suppressed it. All the lysoglycerophospholipids enhanced the transfer, irrespective of the polar head group. Glycerophospholipids therefore have the potential to modify the intestinal absorption of carotenoids.
Rice straw was manually dissected and two main fractions were recovered: a culm and a leaf sheath/blade fraction, in order to evaluate their potential as feedstocks for the recovery of fermentable sugars. In the case of cv. Koshihikari and Milkyqueen, most soft carbohydrates (SCs: glucose, fructose, sucrose, starch, and β-1,3-1,4-glucan) were present in the culms, reaching 47.9% and 89.2% of total SCs in the two main fractions. The results also indicated that β-glucans (cellulose and β-1,3-1,4-glucan) and xylan in the culms were more susceptible to direct enzymatic attack than those in the leaf sheath/blades. Thus the culm has high potential as a new feedstock for the extraction of fermentable sugars in a concentrated form, as compared to whole rice straw and the leaf sheath/blade. In this study, a novel method of separating a culm from the whole rice straw by means of wind power was also evaluated.
Malic enzyme (ME) was purified as an electrophoretically homogenous protein from Rhodopseudomonas palustris No. 7. The molecular weight of ME was estimated to be 650 kDa and that of its subunit, 86 kDa. ME activity was remarkably enhanced by di- and mono-valent cations, and the Ka values for Mg2+ and NH4+ were 0.26 and 0.56 mM respectively. Purified ME used both NAD+ and NADP+ as electron acceptors, with Km values of 0.11 and 1.8 mM. The Km value for L-malate was 1.7 mM using NAD+ as electron acceptor. Gene cloning of the ME indicated that the ME from R. palustris strain No. 7 was composed of 774 amino acids encompassing the ME and phosphotransacetylase domains, although purified ME displayed no phosphotransacetylase activity. ME activity was inhibited by acetyl-CoA, oxaloacetate, and fructose-6-phosphate. These results suggest that ME plays an important role in the metabolic regulation of R. palustris No. 7 under photoheterotrophic conditions.
In this study, rare ginsenoside Rf was transformed into 20(S)-protopanaxatriol (PPT(S)) by glycosidase from Aspergillus niger. By investing the reaction conditions, the optimal conditions were obtained, as follows: pH 5.0, temperature 55 °C, and substrate concentration 1.25 mmol/l. Under optimal conditions, PPT(S) (1.13 μmol) prepared from 1.25 μmol Rf showed a higher yield (90.4%). The enzymatic reaction was analyzed by reversed-phase HPLC, suggesting the transformation pathway: Rf→Rh1(S)→PPT(S).
Biodiesel fuel is favored as a type of carbon neutral energy. To popularize its usage, by-product waste glycerol utilization is a critical problem. We tried to isolate waste glycerol utilizing bacteria, and obtained the alkalo- and halophile bacteria Halomonas sp. KM-1. This strain produced bioplastic poly(3-hydroxybutyrate) (PHB) in a simple medium and diluted waste glycerol as a sole carbon source.
By screening a bacterial population from the soil in Tokyo, Japan, we isolated a boron-tolerant bacterium, strain BTM4c. Strain BTM4c grew under the boron excess conditions with 100 mM boric acid, which is generally toxic to bacteria. Molecular phylogenetic, chemotaxonomic, and physiological data showed that the strain belongs to the genus Rhodococcus, and is to be identified as Rhodococcus baikonurensis.