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31.
Zakataeva NP Romanenkov DV Skripnikova VS Vitushkina MV Livshits VA Kivero AD Novikova AE 《Applied microbiology and biotechnology》2012,93(5):2023-2033
Bacillus strains are used for the industrial production of the purine nucleosides inosine and guanosine, which are raw materials for
the synthesis of the flavor enhancers disodium inosinate and disodium guanylate. An important precursor of purine nucleosides
is 5-phospho-α-d-ribosyl-1-pyrophosphate, which is synthesized by phosphoribosyl pyrophosphate synthetase (PRS, EC 2.7.6.1). Class I PRSs
are widespread in bacteria and mammals, are highly conserved among different organisms, and are negatively regulated by two
end products of purine biosynthesis, adenosine 5′-diphosphate (ADP) and guanosine 5′-diphosphate (GDP). The D52H, N114S, and
L129I mutations in the human PRS isozyme I (PRS1) have been reported to cause uric acid overproduction and gout due to allosteric
deregulation and enzyme superactivity. In this study, to find feedback-resistant Bacillus amyloliquefaciens PRS, the influence of the D58H, N120S, and L135I mutations (corresponding to the D52H, N114S, and L129I mutations in PRS1,
respectively) on PRS enzymatic properties has been studied. Recombinant histidine-tagged wild-type PRS and three mutant PRSs
were expressed in Escherichia coli, purified, and characterized. The N120S and L135I mutations were found to release the enzyme from ADP and GDP inhibition
and significantly increase its sensitivity to inorganic phosphate (Pi) activation. In contrast, PRS with the D58H mutation exhibited nearly identical sensitivity to ADP and GDP as the wild-type
protein and had a notably greater Pi requirement for activation. The N120S and L135I mutations improved B. amyloliquefaciens and Bacillus subtilis purine nucleoside-producing strains. 相似文献
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Nurtaza Aidana Magzumova Gulmira Yessimseitova Assel Karimova Venera Shevtsov Alexandr Silayev Dmitriy Lutsay Viktoriya Ramankulov Yerlan Kakimzhanova Almagul 《In vitro cellular & developmental biology. Plant》2021,57(6):965-976
In Vitro Cellular & Developmental Biology - Plant - Biodiversity conservation requires advanced and effective ex situ plant propagation techniques. The present study was conducted to optimize... 相似文献
35.
Oleg A. Yeshchenko Illya S. Bondarchuk Mykhaylo Yu. Losytskyy Alexandr A. Alexeenko 《Plasmonics (Norwell, Mass.)》2014,9(1):93-101
Strong temperature dependence of surface plasmon enhanced photoluminescence from silver nanoparticles embedded in a silica host matrix has been observed. The quantum yield of photoluminescence increases as the temperature decreases. Such an effect has been rationalized as being the result of an increase in the plasmonic enhancement factor as a consequence of the decrease in the plasmon damping constant. The decrease in the damping constant is due to a reduction in the electron–phonon scattering rate with the decrease in temperature. The temperature dependence of the photoluminescence quantum yield is stronger for small nanoparticles which reflects the strengthening of electron–phonon coupling in silver nanoparticles with a decrease of their size. 相似文献
36.
Vladimir N Anisimov Irina G Popovich Mark A Zabezhinski Peter A Egormin Maria N Yurova Anna V Semenchenko Margarita L Tyndyk Andrey V Panchenko Alexandr P Trashkov Andrey G Vasiliev Nikolai V Khaitsev 《Cell cycle (Georgetown, Tex.)》2015,14(1):46-55
The perinatal (prenatal and early neonatal) period is a critical stage for hypothalamic programming of sexual differentiation as well as for the development of energy and metabolic homeostasis. We hypothesized that neonatal treatment with antidiabetic drug biguanide metformin would positively modify regulation of growth hormone – IGF-1 – insulin signaling pathway slowing down aging and improving cancer preventive patterns in rodents. To test this hypothesis male and female 129/Sv mice were s.c. injected with metformin (100 mg/kg) at the 3rd, 5th and 7th days after birth. Metformin-treated males consumed less food and water and their body weight was decreased as compared with control mice practically over their entire lifespan. There were no significant differences in age-related dynamics of food and water consumption in females and they were heavier than controls. The fraction of mice with regular estrous cycles decreased with age and demonstrated a tendency to decrease in the females neonatally treated with metformin. Neonatal exposure to metformin practically failed to change the extent of hormonal and metabolic parameters in blood serum of male and female mice. In males, neonatal metformin treatment significantly increased the mean life span (+20%, P < 0.05) and slightly increased the maximum life span (+3.5%). In females, the mean life span and median in metformin-treated groups were slightly decreased (−9.1% and −13.8% respectively, P > 0.05) in comparison to controls, whereas mean life span of last 10% survivors and maximum life span were the same as in controls. Almost half (45%) of control male mice and 71.8% male mice neonatally exposed to metformin survived up to 800 d of age, the same age was achieved by 54.3% of mice in control female group and 30% of metformin-treated females (P < 0.03). Thus, neonatal metformin exposure slows down aging and prolongs lifespan in male but not in female mice. 相似文献
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