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Martin Welin J?rg Günter Grossmann Susanne Flodin Tomas Nyman P?l Stenmark Lionel Trésaugues Tetyana Kotenyova Ida Johansson P?r Nordlund Lari Lehti? 《Nucleic acids research》2010,38(20):7308-7319
Human purine de novo synthesis pathway contains several multi-functional enzymes, one of which, tri-functional GART, contains three enzymatic activities in a single polypeptide chain. We have solved structures of two domains bearing separate catalytic functions: glycinamide ribonucleotide synthetase and aminoimidazole ribonucleotide synthetase. Structures are compared with those of homologous enzymes from prokaryotes and analyzed in terms of the catalytic mechanism. We also report small angle X-ray scattering models for the full-length protein. These models are consistent with the enzyme forming a dimer through the middle domain. The protein has an approximate seesaw geometry where terminal enzyme units display high mobility owing to flexible linker segments. This resilient seesaw shape may facilitate internal substrate/product transfer or forwarding to other enzymes in the pathway. 相似文献
104.
Guillermo Hernández-Díaz Alfonso Alexander-Aguilera Agustin Arzaba-Villalba Ida Soto-Rodríguez Hugo S. García 《Prostaglandins, leukotrienes, and essential fatty acids》2010,82(2-3):105-109
Conjugated linoleic acid (CLA) is a naturally occurring group of dienoic derivaties of linoleic acid found mainly in beef and dairy products. CLA has been reported to reduce body fat, as well as to possess anticarcinogenic, antiatherogenic and procatabolic activities in animals. The objective of this study was to evaluate the effect of CLA supplementation to spontaneously hypertensive rats (SHR) on body fat, biochemical parameters of serum related tumor necrosis factor alpha (TNF-α) and resistin secretion. Thirty rats were divided in three groups, the first group of spontaneously hypertensive rats received a standard diet (V-SHR group, n=10), a second group of SHR was fed 1.5% of conjugated linoleic acid (CLA-SHR group, n=10) and the third was the control, non-hypertensive group (KW, n=10) also on a standard diet including 7.5% of sunflower oil during eight weeks.After CLA diet administration, spontaneously hypertensive rats showed a significant reduction in blood pressure, serum glucose, cholesterol and triacylglycerols, together with reduction of index of body fat, pericardic, abdominal and epididymal adipose tissue. These effects were accompanied by a decrease in the secretion of TNF-α and resistin. 相似文献
105.
In this work we have investigated the effect of a pathogenic mitochondrial DNA mutation found in human colon cells, at a functional-molecular level. The mutation results in the amino-acid substitution Tyr19His in subunit I of the human CytcO and it is associated with respiratory deficiency. It was introduced into Rhodobacter sphaeroides, which carries a cytochrome c oxidase (cytochrome aa3) that serves as a model of the mitochondrial counterpart. The residue is situated in the middle of a pathway that is used to transfer substrate protons as well as protons that are pumped across the membrane. The Tyr33His (equivalent residue in the bacterial CytcO) structural variant of the enzyme was purified and its function was investigated. The results show that in the structurally altered CytcO the activity decreased due to slowed proton transfer; proton transfer from an internal proton donor, the highly-conserved Glu286, to the catalytic site was slowed by a factor of ∼ 5, while reprotonation of the Glu from solution was slowed by a factor of ∼ 40. In addition, in the structural variant proton pumping was completely impaired. These results are explained in terms of introduction of a barrier for proton transfer through the D pathway and changes in the coordination of water molecules surrounding the Glu286 residue. The study offers an explanation, at the molecular level, to the link between a specific amino-acid substitution and a pathogenic phenotype identified in human colon cells. 相似文献
106.
Gaia Luziatelli Marten Sørensen Ida Theilade Per Mølgaard 《Journal of ethnobiology and ethnomedicine》2010,6(1):1-23
Background
The Asháninka Native Community Bajo Quimiriki, District Pichanaki, Junín, Peru, is located only 4 km from a larger urban area and is dissected by a major road. Therefore the loss of traditional knowledge is a main concern of the local headman and inhabitants. The present study assesses the state of traditional medicinal plant knowledge in the community and compares the local pharmacopoeia with the one from a related ethnic group.Methods
Fieldwork was conducted between July and September 2007. Data were collected through semi-structured interviews, collection of medicinal plants in the homegardens, forest walks, a walk along the river banks, participant observation, informal conversation, cross check through voucher specimens and a focus group interview with children.Results
Four-hundred and two medicinal plants, mainly herbs, were indicated by the informants. The most important families in terms of taxa were Asteraceae, Araceae, Rubiaceae, Euphorbiaceae, Solanaceae and Piperaceae. Eighty-four percent of the medicinal plants were wild and 63% were collected from the forest. Exotics accounted to only 2% of the medicinal plants. Problems related to the dermal system, digestive system, and cultural belief system represented 57% of all the medicinal applications. Some traditional healers received non-indigenous customers, using their knowledge as a source of income. Age and gender were significantly correlated to medicinal plant knowledge. Children knew the medicinal plants almost exclusively by their Spanish names. Sixteen percent of the medicinal plants found in this community were also reported among the Yanesha of the Pasco Region.Conclusions
Despite the vicinity to a city, knowledge on medicinal plants and cultural beliefs are still abundant in this Asháninka Native Community and the medicinal plants are still available in the surroundings. Nevertheless, the use of Spanish names for the medicinal plants and the shift of healing practices towards a source of income with mainly non-indigenous customers, are signs of acculturation. Future studies on quantification of the use of medicinal plants, dynamics of transmission of ethno-medicinal knowledge to the young generations and comparison with available pharmacological data on the most promising medicinal plants are suggested. 相似文献107.
108.
A wide range of research areas in molecular biology and medical biochemistry require a reliable enzyme classification system, e.g., drug design, metabolic network reconstruction and system biology. When research scientists in the above mentioned areas wish to unambiguously refer to an enzyme and its function, the EC number introduced by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB) is used. However, each and every one of these applications is critically dependent upon the consistency and reliability of the underlying data for success. We have developed tools for the validation of the EC number classification scheme. In this paper, we present validated data of 3788 enzymatic reactions including 229 sub-subclasses of the EC classification system. Over 80% agreement was found between our assignment and the EC classification. For 61 (i.e., only 2.5%) reactions we found that their assignment was inconsistent with the rules of the nomenclature committee; they have to be transferred to other sub-subclasses. We demonstrate that our validation results can be used to initiate corrections and improvements to the EC number classification scheme. 相似文献
109.
A test of the effect of floral color change on pollination effectiveness using artificial inflorescences visited by bumblebees 总被引:2,自引:0,他引:2
Floral color change has been recognized as a pollination strategy, but its relative effectiveness has been evaluated insufficiently
with respect to other floral traits. In this study, effects of floral color change on the visitation pattern of bumblebees
were empirically assessed using artificial flowers. Four inflorescence types were postulated as strategies of flowering behavior:
type 1 has no retention of old flowers, resulting in a small display size; type 2 retains old flowers without nectar production;
type 3 retains old flowers with nectar; and type 4 retains color-changed old flowers without nectar. Effects of these treatments
varied depending on both the total display size (single versus multiple inflorescences) and the pattern of flower-opening.
In the single inflorescence experiment, a large floral display due to the retention of old flowers (types 2–4) enhanced pollinator
attraction, and the number of flower visits per stay decreased with color change (type 4), suggesting a decrease in geitonogamous
pollination. Type-4 plants also reduced the foraging time of bees in comparison with type-2 plants. In the multiple inflorescence
experiment, the retention of old flowers did not contribute to pollinator attraction. When flowering occurred sequentially
within inflorescences, type-4 plants successfully decreased the number of visits and the foraging time in comparison with
type-2 plants. In contrast, floral color change did not influence the number of visits, and it extended the foraging time
when flowering occurred simultaneously within inflorescences but the opening of inflorescences progressed sequentially within
a plant. Therefore, the effectiveness of floral color change is highly susceptible to the display size and flowering pattern
within plants, and this may limit the versatility of the color change strategy in nature. 相似文献
110.
UVB-radiation-induced apoptosis in Jurkat cells: a coordinated fourier transform infrared spectroscopy-flow cytometry study 总被引:1,自引:0,他引:1
Pozzi D Grimaldi P Gaudenzi S Di Giambattista L Silvestri I Morrone S Congiu Castellano A 《Radiation research》2007,168(6):698-705
We studied the induction of apoptosis in Jurkat cells by UVB radiation (wavelength 290-320 nm) at a dose of 310 mJ/ cm2. We combined Fourier transform infrared (FTIR) spectroscopy with flow cytometry to determine whether the combination of both techniques could provide new and improved information about cell modifications. To do this, we looked for correspondences and correlations between spectroscopy and flow cytometry data and found three highly probable spectroscopic markers of apoptosis. The behavior of the wave number shift of both the Amide I beta-sheet component and the area of the 1083 cm(-1) band reproduced, with a high correlation, the behavior of the early apoptotic cell population, while the behavior of the Amide I area showed a high correlation with the early plus late apoptotic cell population. 相似文献