共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
3.
Yukio Yoneda 《Neurochemical research》2017,42(10):2686-2697
l-Theanine (=γ-glutamylethylamide) is an amino acid ingredient in green tea with a structural analogy to l-glutamine (l-GLN) rather than l-glutamic acid (l-GLU), with regards to the absence of a free carboxylic acid moiety from the gamma carbon position. l-theanine markedly inhibits [3H]l-GLN uptake without affecting [3H]l-GLU uptake in cultured neurons and astroglia. In neural progenitor cells with sustained exposure to l-theanine, upregulation of the l-GLN transporter isoform Slc38a1 expression and promotion of both proliferation and neuronal commitment are seen along with marked acceleration of the phosphorylation of mammalian target of rapamycin (mTOR) and relevant downstream proteins. Stable overexpression of Slc38a1 leads to promotion of cellular growth with facilitated neuronal commitment in pluripotent embryonic carcinoma P19 cells. In P19 cells stably overexpressing Slc38a1, marked phosphorylation is seen with mTOR and downstream proteins in a fashion insensitive to the additional stimulation by l-theanine. The green tea amino acid l-theanine could thus elicit pharmacological actions to up-regulate Slc38a1 expression for activation of the mTOR signaling pathway required for cell growth together with accelerated neurogenesis after sustained exposure in undifferentiated neural progenitor cells. In this review, I summarize a novel pharmacological property of the green tea amino acid l-theanine for embryonic and adult neurogenesis with a focus on the endogenous amino acid analog l-GLN. A possible translational strategy is also discussed on the development of dietary supplements and nutraceuticals enriched of l-theanine for the prophylaxis of a variety of untoward impairments and malfunctions seen in patients with different neurodegenerative and/or neuropsychiatric disorders. 相似文献
4.
l-Malic acid is an important component of a vast array of food additives, antioxidants, disincrustants, pharmaceuticals, and cosmetics. Here, we presented a pathway optimization strategy and a transporter modification approach to reconstruct the l-malic acid biosynthesis pathway and transport system, respectively. First, pyruvate carboxylase (pyc) and malate dehydrogenase (mdh) from Aspergillus flavus and Rhizopus oryzae were combinatorially overexpressed to construct the reductive tricarboxylic acid (rTCA) pathway for l-malic acid biosynthesis. Second, the l-malic acid transporter (Spmae) from Schizosaccharomyces pombe was engineered by removing the ubiquitination motification to enhance the l-malic acid efflux system. Finally, the l-malic acid pathway was optimized by controlling gene expression levels, and the final l-malic acid concentration, yield, and productivity were up to 30.25 g L?1, 0.30 g g?1, and 0.32 g L?1 h?1 in the resulting strain W4209 with CaCO3 as a neutralizing agent, respectively. In addition, these corresponding parameters of pyruvic acid remained at 30.75 g L?1, 0.31 g g?1, and 0.32 g L?1 h?1, respectively. The metabolic engineering strategy used here will be useful for efficient production of l-malic acid and other chemicals. 相似文献
5.
Yuta Miki Seiji Okazaki Yasuhisa Asano 《Journal of industrial microbiology & biotechnology》2017,44(4-5):667-675
We successfully engineered a new enzyme that catalyzes the formation of d-Ala amide (d-AlaNH2) from d-Ala by modifying ATP-dependent d-Ala:d-Ala ligase (EC 6.3.2.4) from Thermus thermophilus, which catalyzes the formation of d-Ala-d-Ala from two molecules of d-Ala. The new enzyme was created by the replacement of the Ser293 residue with acidic amino acids, as it was speculated to bind to the second d-Ala of d-Ala-d-Ala. In addition, a replacement of the position with Glu performed better than that with Asp with regards to specificity for d-AlaNH2 production. The S293E variant, which was selected as the best enzyme for d-AlaNH2 production, exhibited an optimal activity at pH 9.0 and 40 °C for d-AlaNH2 production. The apparent K m values of this variant for d-Ala and NH3 were 7.35 mM and 1.58 M, respectively. The S293E variant could catalyze the synthesis of 9.3 and 35.7 mM of d-AlaNH2 from 10 and 50 mM d-Ala and 3 M NH4Cl with conversion yields of 93 and 71.4 %, respectively. This is the first report showing the enzymatic formation of amino acid amides from amino acids. 相似文献
6.
Qinjian Zhu Xiaomei Zhang Yuchang Luo Wen Guo Guoqiang Xu Jinsong Shi Zhenghong Xu 《Applied microbiology and biotechnology》2015,99(4):1665-1673
The direct fermentative production of l-serine by Corynebacterium glutamicum from sugars is attractive. However, superfluous by-product accumulation and low l-serine productivity limit its industrial production on large scale. This study aimed to investigate metabolic and bioprocess engineering strategies towards eliminating by-products as well as increasing l-serine productivity. Deletion of alaT and avtA encoding the transaminases and introduction of an attenuated mutant of acetohydroxyacid synthase (AHAS) increased both l-serine production level (26.23 g/L) and its productivity (0.27 g/L/h). Compared to the parent strain, the by-products l-alanine and l-valine accumulation in the resulting strain were reduced by 87 % (from 9.80 to 1.23 g/L) and 60 % (from 6.54 to 2.63 g/L), respectively. The modification decreased the metabolic flow towards the branched-chain amino acids (BCAAs) and induced to shift it towards l-serine production. Meanwhile, it was found that corn steep liquor (CSL) could stimulate cell growth and increase sucrose consumption rate as well as l-serine productivity. With addition of 2 g/L CSL, the resulting strain showed a significant improvement in the sucrose consumption rate (72 %) and the l-serine productivity (67 %). In fed-batch fermentation, 42.62 g/L of l-serine accumulation was achieved with a productivity of 0.44 g/L/h and yield of 0.21 g/g sucrose, which was the highest production of l-serine from sugars to date. The results demonstrated that combined metabolic and bioprocess engineering strategies could minimize by-product accumulation and improve l-serine productivity. 相似文献
7.
F. Krüger 《Helgoland Marine Research》1969,19(2):205-215
Considering an incomplete growth curve of the codGadus morhua,Knight (1968) questioned the asymptotic curvature of growth in fishes, which easily may be shown in complete growth curves illustrating the attainment of maximum size. It is also possible to calculate maximum size employing theFord-Walford formula. Maximum size, calculated in this manner, may also be used in theBertalanffy function. For other mathematical growth formulations different maximum sizes would be obtained. The numerical value of the maximum size depends upon the mathematical interpretation of the growth process. Therefore it always represents a mathematical parameter without biological meaning. It is shown that data ofKetchen (Forrester 1966) on growth in ♂ ♂ of the flat fishEopsetta jordani may be much better represented by the new growth formula (Krüger 1965) than by theBertalanffy function. 相似文献
8.
Sacheenkumar S. Raval Mahesh Kumar Mahatma Koushik Chakraborty Sujit Kumar Bishi Amrit Lal Singh Khyati J. Rathod Jaymin K. Jadav Jayesh M. Sanghani Munniben K. Mandavia Harsukh P. Gajera Baljibhai A. Golakiya 《Plant Growth Regulation》2018,84(3):493-505
Various metabolites were analyzed in groundnut genotypes grown under varying temperature regimes (based on date of sowing). Four contrasting groundnut genotypes viz. ICGS44 (high-temperature tolerant), AK159 and GG7 (moderately-high-temperature tolerant), and DRG1 (high-temperature sensitive) were grown at three different temperature regimes i.e., low (early date of sowing), normal (normal date of sowing) and high temperature (late date of sowing) under field conditions. Untargeted metabolomic analysis of leaf tissue was performed by GC–MS, while targeted metabolite profiling was carried out by HPLC (polyamines) and UPLC-MS/MS (phenolics) at both the pegging and pod filling stages. Untargeted metabolomic profiling revealed exclusive expression/induction of beta-d-galactofuranoside, l-threonine, hexopyranose, d-glucopyranose, stearic acid, 4-ketoglucose, d-gulose, 2-o-glycerol-alpha-d-galactopyranoside and serine in ICGS44 during the pegging stage under high-temperature conditions. During the pod filling stage at higher temperature, alpha-d-galactoside, dodecanedioic acid, 1-nonadecene, 1-tetradecene and beta-d-galactofuranose were found to be higher in both ICGS44 and GG7. Moreover, almost all the metabolites detected by GC–MS were found to be higher in GG7, except beta-d-galactopyranoside, beta-d-glucopyranose, inositol and palmitic acid. Accumulation of putrescine was observed to be higher during low-temperature stress, while agmatine showed constitutive expression in all the genotypes, irrespective of temperature regime and crop growth stage. Interestingly, spermidine was observed only in the high-temperature tolerant genotype ICGS44. In our study, we found a higher accumulation of cinnamic acid, caffeic acid, salicylic acid and vanillic acid in ICGS44 compared to that of other genotypes at the pegging stage, whereas catechin and epicatechin were found during the pod filling stage in response to high-temperature stress, suggesting their probable roles in heat-stress tolerance in groundnut. 相似文献
9.
The differentiation of tissues is closely connected with the proteosynthesis. One can therfore assume that tissues with different types of cell growth (meristematic or elongation growth) and with different degrees of differentiation are different in their protein composition. In order to compare the protein composition of different plant organs, the method of disc electrophoresis on a polyacrylamide gel has been used by some authors. As compared with other methods used up to now, e. g. isolating proteins on DEAE cellulose or in Sephadex, this method does not need so much material and its resolution ability seems to be higher. It is also quicker and enables the study of several samples simultaneously. Its disadvantage is that proteins can be identified mainly by means of Rf and their quantity, measured from the intensity of staining of individual fractions in the gel, which may be misleading due to different sorption capacity of different proteins (Fri?Fri?ová 1967). None the less, it is good for comparison of protein composition of individual parts of the plant body. Different methods have been used to compare protein composition of individual growth zones in roots.Barsky,Ivanov andPushakova (1965) used luminiscence microscopy and found that in maize roots it is not possible to find substantial differences by this method.Morgan andReith (1954) arrived at similar conclusions. On the other hand,Steward et al. (1965) andMorris (1966) found qualitative differences in protein composition of different parts of pea roots using acrylamide electrophoresis. The results of the last named authors show considerable discrepancies in details, due perhaps to a different method of extraction (buffer, pH, purifying method). We have used acrylamide gel electrophoresis for investigating proteins in precisely defined growth zones of theVicia faba root. 相似文献
10.
Ying Yang Zhenlong Wu Sichao Jia Sudath Dahanayaka Shuo Feng Cynthia J. Meininger Catherine J. McNeal Guoyao Wu 《Amino acids》2015,47(9):1909-1920
This study was conducted with rats to determine the safety of long-term dietary supplementation with l-arginine. Beginning at 6 weeks of age, male and female rats were fed a casein-based semi-purified diet containing 0.61 % l-arginine and received drinking water containing l-arginine-HCl (0, 1.8, or 3.6 g l-arginine/kg body-weight/day; n = 10/group). These supplemental doses of l-arginine were equivalent to 0, 286, and 573 mg l-arginine/kg body-weight/day, respectively, in humans. After a 13-week supplementation period, blood samples were obtained from rats for biochemical analyses. Supplementation with l-arginine increased plasma concentrations of arginine, ornithine, proline, homoarginine, urea, and nitric oxide metabolites without affecting those for lysine, histidine, or methylarginines, while reducing plasma concentrations of ammonia, glutamine, free fatty acids, and triglycerides. l-Arginine supplementation enhanced protein gain and reduced white-fat deposition in the body. Based on general appearance, feeding behavior, and physiological parameters, all animals showed good health during the entire experimental period; Plasma concentrations of all measured hormones (except leptin) did not differ between control and arginine-supplemented rats. l-Arginine supplementation reduced plasma levels of leptin. Additionally, l-arginine supplementation increased l-arginine:glycine amidinotransferase activity in kidneys but not in the liver or small intestine, suggesting tissue-specific regulation of enzyme expression by l-arginine. Collectively, these results indicate that dietary supplementation with l-arginine (e.g., 3.6 g/kg body-weight/day) is safe in rats for at least 91 days. This dose is equivalent to 40 g l-arginine/kg body-weight/day for a 70-kg person. Our findings help guide clinical studies to determine the safety of long-term oral administration of l-arginine to humans. 相似文献
11.
Shaoxiong Liang Dacheng Gao Huanhuan Liu Cheng Wang Jianping Wen 《Journal of industrial microbiology & biotechnology》2018,45(8):681-696
As an important feedstock monomer for the production of biodegradable stereo-complex poly-lactic acid polymer, d-lactate has attracted much attention. To improve d-lactate production by microorganisms such as Lactobacillus delbrueckii, various fermentation conditions were performed, such as the employment of anaerobic fermentation, the utilization of more suitable neutralizing agents, and exploitation of alternative nitrogen sources. The highest d-lactate titer could reach 133 g/L under the optimally combined fermentation condition, increased by 70.5% compared with the control. To decipher the potential mechanisms of d-lactate overproduction, the time-series response of intracellular metabolism to different fermentation conditions was investigated by GC–MS and LC–MS/MS-based metabolomic analysis. Then the metabolomic datasets were subjected to weighted correlation network analysis (WGCNA), and nine distinct metabolic modules and eight hub metabolites were identified to be specifically associated with d-lactate production. Moreover, a quantitative iTRAQ–LC–MS/MS proteomic approach was employed to further analyze the change of intracellular metabolism under the combined fermentation condition, identifying 97 up-regulated and 42 down-regulated proteins compared with the control. The in-depth analysis elucidated how the key factors exerted influence on d-lactate biosynthesis. The results revealed that glycolysis and pentose phosphate pathways, transport of glucose, amino acids and peptides, amino acid metabolism, peptide hydrolysis, synthesis of nucleotides and proteins, and cell division were all strengthened, while ATP consumption for exporting proton, cell damage, metabolic burden caused by stress response, and bypass of pyruvate were decreased under the combined condition. These might be the main reasons for significantly improved d-lactate production. These findings provide the first omics view of cell growth and d-lactate overproduction in L. delbrueckii, which can be a theoretical basis for further improving the production of d-lactate. 相似文献
12.
Simple and convergent synthesis of a tetra- and a trisaccharide portions of an antitumor compound Julibroside J28, isolated from Albizia julibrissin, that showed significant in vitro antitumor activity against HeLa, Bel-7402 and PC-3M-1E8 cancer cell lines is reported. The tetrasaccharide has been synthesized as its p-methoxyphenyl glycoside starting from commercially available d-glucose, l-rhamnose and l-arabinose. The trisaccharide part has been synthesized from commercially available N-acetyl d-glucosamine, d-fucose and d-xylose using simple protecting group manipulations. Sulfuric acid immobilized on silica has been used successfully as a Brönsted acid catalyst for the crucial glycosylation steps. 相似文献
13.
Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key catalyst of CO2 fixation in nature. RuBisCO forms I, II, and III catalyze CO2 fixation reactions, whereas form IV, also called the RuBisCO-like protein (RLP), is known to have no carboxylase or oxygenase activities. Here, we describe an RLP in Ochrobactrum anthropi ATCC 49188 (Oant_3067; HamA) that functions as an oxygenase in the metabolism of d-hamamelose, a branched-chain hexose found in most higher plants. The d-hamamelose pathway is comprised of five previously unknown enzymes: d-hamamelose dehydrogenase, d-hamamelono-lactonase, d-hamamelonate kinase, d-hamamelonate-2′,5-bisphosphate dehydrogenase (decarboxylating), and the RLP 3-keto-d-ribitol-1,5-bisphosphate (KRBP) oxygenase, which converts KRBP to 3-d-phosphoglycerate and phosphoglycolate. HamA represents the first RLP catalyzing the O2-dependent oxidative C–C bond cleavage reaction, and our findings may provide insights into its applications in oxidative cleavage of organic molecules. 相似文献
14.
In order to investigate chemical evolution in interstellar molecular clouds, enantiomer-selective photo-induced chemical reactions between an amino acid and disaccharides in the gas phase were examined using a tandem mass spectrometer containing an electrospray ionization source and a cold ion trap. Ultraviolet photodissociation mass spectra of cold gas-phase noncovalent complexes of protonated tryptophan (Trp) enantiomers with disaccharides consisting of two d-glucose units, such as d-maltose or d-cellobiose, were obtained by photoexcitation of the indole ring of Trp. NH2CHCOOH loss via cleavage of the Cα–Cβ bond in Trp induced by hydrogen atom transfer from the NH3 + group of a protonated Trp was observed in a noncovalent heterochiral H+(l-Trp)(d-maltose) complex. In contrast, a photo-induced chemical reaction forming the product ion with m/z 282 occurs in homochiral H+(d-Trp)(d-maltose). For d-cellobiose, both NH2CHCOOH elimination and the m/z 282 product ion were observed, and no enantiomer-selective phenomena occurred. The m/z 282 product ion indicates that the photo-induced C-glycosylation, which links d-glucose residues to the indole moiety of Trp via a C–C bond, can occur in cold gas-phase noncovalent complexes, and its enantiomer-selectivity depends on the structure of the disaccharide. 相似文献
15.
Boreal forest dynamics in north-eastern Sweden during the last 10,000 years based on pollen analysis
Lena Barnekow Petra Bragée Dan Hammarlund Natalie St. Amour 《Vegetation History and Archaeobotany》2008,17(6):687-700
A pollen record obtained from a 2.2-m sediment succession deposited in a small lake in the province of Västerbotten, north-eastern Sweden, reveals the presence of continuous forest cover since 8,500 calendar years before present (cal b.p.). Forest with abundant Pinus (pine) and Betula (birch) initially colonized the area, followed by a dominance of deciduous trees, primarily Betula, from ca. 8,000 to ca. 3,200 cal b.p. Pollen accumulation rates of Quercus (oak), Ulmus (elm) and Tilia (linden) suggest the possible local presence of these thermophilous tree species during this period. The climate gradually became colder and moister around 3,500 cal b.p. and an increased abundance of Sphagnum spores indicates paludification. Picea (spruce) became established around 3,200 cal b.p. and less than 500 years later this was the dominant tree species around the lake. The fire frequency as inferred from charcoal particles exhibits a general increase from ca. 3,000 cal b.p. with subsequent charcoal accumulation maxima at around 2,800 cal b.p., 1,700 cal b.p. and in recent time. The human influence on vegetation was significant during the last 200–300 years. Soil erosion increased substantially and fern spores amount to ca. 55% of the total pollen assemblage in the uppermost samples. These results suggest an extensive anthropogenic impact on the local forest ecosystem, with abundant logging, burning and ditching in the vicinity of the lake. Independent evidence of sub-recent human-induced environmental change is provided by historical accounts. Complementary information on catchment soil development and aquatic nutrient status was provided by records of magnetic susceptibility and elemental carbon, and nitrogen contents obtained from the same sediment core. 相似文献
16.
Jesús Salvador López-Bucio Javier Raya-González Gustavo Ravelo-Ortega León Francisco Ruiz-Herrera Maricela Ramos-Vega Patricia León José López-Bucio Ángel Arturo Guevara-García 《Plant molecular biology》2018,96(4-5):339-351
Key message
The function and components of l-glutamate signaling pathways in plants have just begun to be elucidated. Here, using a combination of genetic and biochemical strategies, we demonstrated that a MAPK module is involved in the control of root developmental responses to this amino acid.Abstract
Root system architecture plays an essential role in plant adaptation to biotic and abiotic factors via adjusting signal transduction and gene expression. l-Glutamate (l-Glu), an amino acid with neurotransmitter functions in animals, inhibits root growth, but the underlying genetic mechanisms are poorly understood. Through a combination of genetic analysis, in-gel kinase assays, detailed cell elongation and division measurements and confocal analysis of expression of auxin, quiescent center and stem cell niche related genes, the critical roles of l-Glu in primary root growth acting through the mitogen-activated protein kinase 6 (MPK6) and the dual specificity serine–threonine–tyrosine phosphatase MKP1 could be revealed. In-gel phosphorylation assays revealed a rapid and dose-dependent induction of MPK6 and MPK3 activities in wild-type Arabidopsis seedlings in response to l-Glu. Mutations in MPK6 or MKP1 reduced or increased root cell division and elongation in response to l-Glu, possibly modulating auxin transport and/or response, but in a PLETHORA1 and 2 independent manner. Our data highlight MPK6 and MKP1 as components of an l-Glu pathway linking the auxin response, and cell division for primary root growth.17.
18.
Xiaoyu Chen Yaoxuan Li Wan Chen Zhihuan Nong Jianping Huang Chunxia Chen 《Neurochemical research》2016,41(11):3032-3041
Memory decline is characteristic of aging and age-related neurodegenerative disorders. This study was designed to investigate the protective effect of hyperbaric oxygen (HBO) against cognitive impairment induced by d-galactose (d-gal) in mice. d-gal was intraperitoneally injected into mice daily for 8 weeks to establish the aging model. HBO was simultaneously administered once daily. The results indicate that HBO significantly reversed D-gal-induced learning and memory impairments. Studies on the potential mechanisms of this action showed that HBO significantly reduced oxidative stress by increasing superoxide dismutase, glutathione peroxidase, and catalase levels, as well as the total anti-oxidation capability, while decreasing the content of malondialdehyde, nitric oxide, and nitric oxide synthase in the hippocampal CA1 region. HBO also inhibited advanced glycation end-product formation and decreased levels of tumor necrosis factor-α and interleukin-6. Moreover, HBO significantly attenuated d-gal-induced pathological injury in the hippocampus, as well as β-amyloid protein1?42 expression and retained BDNF expression. Furthermore, HBO decreased p16, p21 and p53 gene and protein expression in the hippocampus of d-gal-treated mice. In conclusion, the protective effect of HBO against d-gal-induced cognitive impairment was mainly due to its ability to reduce oxidative damage, suppress inflammatory responses, and regulate aging-related gene expression. 相似文献
19.
Many studies have been made on ribosomes both in plant and animal material, on account of their importance in the proteosynthesis of protein. In plant material, studies have been made on the pea by Ts'o andBonner (1956), Ts'o,Bonner andVinograd (1958),Setterfield et al. (1960) andSisakyan et al. (1963). Ribosome from spinach were investigated byLyttleton (1962) andMurakami (1963) and fromClivia byMikulská et al. (1962). As part of a wider study of the mechanism of biosynthesis of nucleic acids in apple trees, we isolated ribosomes from the young green fruit and studied them by means of electron microscopy. Young apples were selected because cell division is very intense at this stage of growth of the apple. 相似文献
20.
Karin Förster-Fromme Sarah Schneider Georg A. Sprenger Christoph Albermann 《Biotechnology letters》2017,39(2):219-226