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141.
ABSTRACT Flacca, tomato mutant in which the last step of ABA biosynthesis is blocked, displays changes both in polyamine content (especially the ratio between free and conjugated forms) and in ornithine-, arginine- and S- adenosylmethionine decarboxylase activities. Arginine decarboxylase activity is higher compared to that of ornithine decarboxylase especially in older plants (seven internode stage), being on line with its regulatory role. However this activity is not sufficient to justify the polyamine content, in particular of conjugated forms (disappearance of TCA-insoluble conjugates and dramatic decrease of TCA-soluble ones). These results are in favour of a multifunctional competition of many responses to hormone action. 相似文献
142.
AbstractCalcium is an important macronutrient for both prokaryotes and eukaryotes. It acts as an important second messenger mediating rapid response to environmental conditions. The present investigation deals with proteome profiling of Anabaena 7120 and its derivative ntcA mutant in response to varied calcium doses (0, 1 and 10?mM CaCl2). Concentration of 1?mM CaCl2 salt was the optimum concentration whereas 10?mM CaCl2 was the inhibitory concentration for both the wild type and mutant strains. The results showed highly significant alteration in terms of protein abundance and differential response related to key processes of photosynthesis, energy and metabolism, nitrogen metabolism, oxidative and antioxidative defence, transport and signalling and fatty acid metabolism. In the wild type proteins related to photosynthesis and nitrogen metabolism showed upregulation at 1?mM CaCl2 concentration while antioxidative defence related proteins were down-regulated. In the mutant however, proteins related to photosynthesis and nitrogen metabolism exhibited severe down-regulation. Some hypothetical proteins were also realized during proteome analysis. Overall, our results suggested that NtcA have a potential role in regulation of calcium ion dependent key processes underlying in various metabolic activities of the cyanobacterium Anabaena 7120. 相似文献
143.
Dongxin Zhao Zhongxian Huang Jie Liu Li Ma Juan He 《Preparative biochemistry & biotechnology》2013,43(10):914-919
AbstractZinc finger protein ZNF191(243–368), the zinc finger region of ZNF191, is potentially associated with cell proliferation in hepatocellular carninoma. A His-tag expression system was used to express and purify proteins with mutations in the zinc finger 3 of ZNF191(243–368) for analysis of protein properties, structure, and functions. The purification of the His-tag fusion proteins was simpler and faster than that of the ZNF191(243–368) inclusion bodies. The properties and structures of the His-tag fusion mutant proteins were investigated using spectrographic techniques and DNA hydrolysis experiment. The His6-tag system could be used to express ZNF191(243–368). The presence of the His6-tag at the N-terminus of ZNF191(243–368) did not evidently affect its properties and structure. However, the site-directed mutations in zinc finger 3 affected the structure of the protein. The DNA hydrolase activity of His6-ZF-F3/H4 suggested that four histidines in zinc finger 3 might form a structure similar to that of the active center in a hydrolase. This work reports that continuous histidines need to form a certain structure for specific functions, and provides new insights into the design of an artificial nuclease. 相似文献
144.
Anil K. Bidwai Cassandra MeyenHeather Kilheeney Damian WroblewskiLidia B. Vitello James E. Erman 《Biochimica et Biophysica Acta - Proteins and Proteomics》2013,1834(1):137-148
Three yeast cytochrome c peroxidase (CcP) variants with apolar distal heme pockets have been constructed. The CcP variants have Arg48, Trp51, and His52 mutated to either all alanines, CcP(triAla), all valines, CcP(triVal), or all leucines, CcP(triLeu). The triple mutants have detectable enzymatic activity at pH 6 but the activity is less than 0.02% that of wild-type CcP. The activity loss is primarily due to the decreased rate of reaction between the triple mutants and H2O2 compared to wild-type CcP. Spectroscopic properties and cyanide binding characteristics of the triple mutants have been investigated over the pH stability region of CcP, pH 4 to 8. The absorption spectra indicate that the CcP triple mutants have hemes that are predominantly five-coordinate, high-spin at pH 5 and six-coordinate, low-spin at pH 8. Cyanide binding to the triple mutants is biphasic indicating that the triple mutants have two slowly-exchanging conformational states with different cyanide affinities. The binding affinity for cyanide is reduced at least two orders of magnitude in the triple mutants compared to wild-type CcP and the rate of cyanide binding is reduced by four to five orders of magnitude. Correlation of the reaction rates of CcP and 12 distal pocket mutants with H2O2 and HCN suggests that both reactions require ionization of the reactants within the distal heme pocket allowing the anion to bind the heme iron. Distal pocket features that promote substrate ionization (basic residues involved in base-catalyzed substrate ionization or polar residues that can stabilize substrate anions) increase the overall rate of reaction with H2O2 and HCN while features that inhibit substrate ionization slow the reactions. 相似文献
145.
Sen Wang Fei Zheng Meijing Zhang Jun Tu Yanping Chen Jianhua Yuan Qingchang Meng 《Phyton》2020,89(4):861-871
Endosperm mutants are critical to the studies on both starch synthesis
and metabolism and genetic improvement of starch quality in maize. In the present study, a novel maize endosperm mutant A0178 of natural variation was used
as the experimental material and identified and then characterized. Through phenotypic identification, genetic analysis, main ingredients measurement and
embryo rescue, development of genetic mapping population from A0178, the
endosperm mutant gene was located. The results showed that the mutant exhibited
extremely low germination ability as attributed to the inhibited embryo development, and amounts of sugars were accumulated in the mutant seeds and more
sugars content was detected at 23 days after pollination (DAP) in A0178 than
B73. Employing genetic linkage analysis, the mutant trait was mapped in the
bin 5.04 on chromosome 5. Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding
region of the mutant brittle-1 (bt1), the adenylate translocator encoding gene
involved in the starch synthesis. The single base insertion in the coding region
cause frameshift mutation, early termination and lose of function of Brittle-1
(BT1). All results suggested that bt1 is a novel allelic gene and the causal gene
of this endosperm mutant, providing insights on the mechanism of endosperm formation in maize. 相似文献
146.
147.
K. P. Akhtar G. Sarwar H. M.I. Arshad 《Archives Of Phytopathology And Plant Protection》2013,46(4):320-330
Charcoal rot caused by Macrophomina phaseolina is a serious disease of sesame in Pakistan. M. phaseolina sesame isolate was subjected to growth rate test at 10, 15, 20, 25, 30, 35 and 40°C. The optimum temperature for fungal growth and microsclerotia production was found to be 30–35°C. Gray to black, radial fungal colonies with intermediate mycelial growth and jet black oval to round microsclerotia were observed at this optimum range. M. phaseolina was found to be pathogenic against all the 18 tested plant species and this pathogenicity proved its necrophytic behavior. Seed infection efficiency of M. phaseolina was 100% with significant reduction in seed index. For two consecutive years 21 mutants/varieties were screened in the field for their reactions to charcoal rot disease. During 2007 three mutants NS11704S1, NS11304S2 and NS26004 were ranked as resistant while others were moderately resistant to highly susceptible. During 2008 all mutants showed a susceptible to highly susceptible reaction with variable disease reactions. All over screening results revealed that four mutants viz, NS13P1, NS163-1, NS270P1 and NS26004 showed about 50% stand with consistent performance during both years under optimum disease conditions and can be used to manage the disease following the disease management strategies, however in the future improvement for high seed yield along with resistance is a prerequisite for sustainable high production. 相似文献
148.
149.
Jianwei He Linan Xu Zhiyuan Zou Nobuhiro Ueyama Hui Li Akio Kato 《Journal of biomolecular structure & dynamics》2013,31(10):1101-1110
Chicken cystatin (cC) mutant I66Q is located in the hydrophobic core of the protein and increases the propensity for amyloid formation. Here, we demonstrate that under physiological conditions, the replacement of Ile with the Gln in the I66Q mutant increases the susceptibility for the disulfide bond Cys71–Cys81 to be reduced when compared to the wild type (WT) cC. Molecular dynamics (MD) simulations under conditions favoring cC amyloid fibril formation are in agreement with the experimental results. MD simulations were also performed to investigate the impact of disrupting the Cys71–Cys81 disulfide bond on the conformational stability of cC at the atomic level, and highlighted major disruption to the cC appendant structure. Domain swapping and extensive unfolding has been proposed as one of the possible mechanisms initiating amyloid fibril formation by cystatin. Our in silico studies suggest that disulfide bond formation between residues Cys95 and Cys115 is necessary to maintain conformational stability of the I66Q mutant following breakage of the Cys71–Cys81 disulfide bridge. Subsequent breakage of disulfide bond Cys95–Cys115 resulted in large structural destabilization of the I66Q mutant, which increased the α–β interface distance and expanded the hydrophobic core. These experimental and computational studies provide molecular-level insight into the relationship between disulfide bond formation and progressive unfolding of amyloidogenic cC mutant I66Q. An animated Interactive 3D Complement (I3DC) is available in Proteopedia at http://proteopedia.org/w/Journal:JBSD:23 相似文献
150.
Four components of ovomucoid were digested exhaustively and four kinds of glycopeptide corresponding to the four components were separated by gel filtration. Each glycopeptide was shown to be homogenious by paper chromatography and paper electrophoresis. Molar ratios of carbohydrate components of these glycopeptides varied to some extent but the amino acid compositions of these glycopeptides were essentially identical with each other with the exception of alanine. Aspartic acid and threonine were predominant amino acids in the all glycopeptides. It is most likely that the modes of linkages between polysaccharide and protein in individual ovomucoid I, II, III and IV are essentially the same, and that the carbohydrate moiety is linked to the protein via asparaginyl residue or the hydroxyl group of threonine, although the possibility of the linkages to glutamine and serine can not be excluded. 相似文献