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81.
We have used the measurements of the histone fluorescence parameters to study the influence of the ionic strength on histone-DNA and histone-histone interactions in reconstructed nucleosomes. The ionic strength increase lead to the two-stage nucleosome dissociation. The dimer H2A-H2B dissociates at the first stage and the tetramer (H3-H4)2 at the second one. The dimer H2A-H2B dissociation from nucleosome is a two-stage process also. The ionic bonds between (H2A-H2B) histone dimer and DNA break at first and then the dissociation of dimer from histone tetramer (H3-H4)2 occurs. According to the proposed model the dissociation accompanying a nucleosome "swelling" and an increase of DNA curvature radius. It was shown that the energy of electrostatic interactions between histone dimer and DNA is sufficiently less than the energy of dimer-tetramer interaction. We propose that the nucleosome DNA ends interact with the dimer and tetramer simultaneously. The calculated number (approximately 30 divided by 40) of ionic bonds between DNA and histone octamer globular part practically coincides with the number of exposed cationic groups on the surface of octamer globular head. On this basis we have assumed that the spatial distribution of these groups is precisely determined, which explains the high evolutionary conservatism of the histone primary structure. 相似文献
82.
S.N. Khrapunov A.I. Dragan A.F. Protas G.D. Berdyshev 《International journal of biological macromolecules》1984,6(1):26-30
Using the methods of spectrophotometry, spectrofluorimetry, light scattering and gel filtration, it was shown that, at pH 5.6 and 7.4 and various ionic strengths, the histone tetramer (H3-H4)2 may have several structural states with different packing of the polypeptide chains of histones H3 and H4. Two structural changes of the tetramer (H3-H4)2 at pH 7.4 in the ranges 0.1–0.3 m and 0.7–0.9 m NaCl were observed. In the high ionic strength solution, the tetramer (H3-H4)2 had a more compact structure at pH 7.4 than at pH 5.6. At pH 3.0 destruction of the histone tetramer (H3-H4)2 and formation of non-specific aggregates took place. 相似文献
83.
84.
Dragan Miscevic Ju-Yi Mao Murray Moo-Young Chih-Hsiung Perry Chou 《Biotechnology and bioengineering》2020,117(5):1304-1315
A propanologenic (i.e., 1-propanol-producing) bacterium Escherichia coli strain was previously derived by activating the genomic sleeping beauty mutase (Sbm) operon. The activated Sbm pathway branches out of the tricarboxylic acid (TCA) cycle at the succinyl-CoA node to form propionyl-CoA and its derived metabolites of 1-propanol and propionate. In this study, we targeted several TCA cycle genes encoding enzymes near the succinyl-CoA node for genetic manipulation to identify the individual contribution of the carbon flux into the Sbm pathway from the three TCA metabolic routes, that is, oxidative TCA cycle, reductive TCA branch, and glyoxylate shunt. For the control strain CPC-Sbm, in which propionate biosynthesis occurred under relatively anaerobic conditions, the carbon flux into the Sbm pathway was primarily derived from the reductive TCA branch, and both succinate availability and the SucCD-mediated interconversion of succinate/succinyl-CoA were critical for such carbon flux redirection. Although the oxidative TCA cycle normally had a minimal contribution to the carbon flux redirection, the glyoxylate shunt could be an alternative and effective carbon flux contributor under aerobic conditions. With mechanistic understanding of such carbon flux redirection, metabolic strategies based on blocking the oxidative TCA cycle (via ∆sdhA mutation) and deregulating the glyoxylate shunt (via ∆iclR mutation) were developed to enhance the carbon flux redirection and therefore propionate biosynthesis, achieving a high propionate titer of 30.9 g/L with an overall propionate yield of 49.7% upon fed-batch cultivation of the double mutant strain CPC-Sbm∆sdhA∆iclR under aerobic conditions. The results also suggest that the Sbm pathway could be metabolically active under both aerobic and anaerobic conditions. 相似文献
85.
Verena Hess Olga Oyrik Dragan Trifunovi? Volker Müller 《Applied and environmental microbiology》2015,81(14):4711-4719
The acetogenic bacterium Acetobacterium woodii is able to reduce CO2 to acetate via the Wood-Ljungdahl pathway. Only recently we demonstrated that degradation of 1,2-propanediol by A. woodii was not dependent on acetogenesis, but that it is disproportionated to propanol and propionate. Here, we analyzed the metabolism of A. woodii on another diol, 2,3-butanediol. Experiments with growing and resting cells, metabolite analysis and enzymatic measurements revealed that 2,3-butanediol is oxidized in an NAD+-dependent manner to acetate via the intermediates acetoin, acetaldehyde, and acetyl coenzyme A. Ethanol was not detected as an end product, either in growing cultures or in cell suspensions. Apparently, all reducing equivalents originating from the oxidation of 2,3-butanediol were funneled into the Wood-Ljungdahl pathway to reduce CO2 to another acetate. Thus, the metabolism of 2,3-butanediol requires the Wood-Ljungdahl pathway. 相似文献
86.
Peters BA Kan Z Sebisanovic D Pujara K Wang Z Hong P Chow B Stinson J Carlton VE Pham TQ Stern H Waring P Hillan KJ Eberhard DA de Sauvage F Zheng J Faham M Seshagiri S 《Nature methods》2007,4(9):713-715
The discovery of somatic mutations in cancer tissue is extremely laborious, time-consuming and costly. In an evaluation comparing mismatch repair detection (MRD) against Sanger sequencing for somatic-mutation detection, we found that MRD had a specificity of 96% and a sensitivity of 92%. Our results showed that MRD is a robust and cost-effective alternative to Sanger sequencing for identifying somatic mutations in human tumors. 相似文献
87.
Laura K. Schnackenberg Yvonne P. Dragan Michael D. Reily Donald G. Robertson Richard D. Beger 《Metabolomics : Official journal of the Metabolomic Society》2007,3(2):87-100
Single low and high doses of several compounds with known renal toxic effects (para-aminophenol, puromycin aminonucleoside,
sodium chromate, and hexachlorobutadiene,) or known liver toxic effects (galactosamine, allyl alcohol, and thioacetamide)
were administered to male Wistar rats in groups of 4 or 8 for each compound. Predose urine samples (Day 0) and samples from
post-dosing (Days 1–4) were collected for each rat and monitored by 1D 1H NMR. Principal component analysis (PCA) of the NMR spectra was used to investigate differences between dose levels for each
compound individually. The findings from PCA at both dose levels for each compound were examined in the context of the corresponding
clinical chemistry and pathology data collected during the study. The PCA clustering of NMR spectra from rats dosed with each
individual compound were shown to be associated with the measured levels of creatinine, BUN, AST, ALT and histopathology findings.
Finally, scaled-to-maximum, aligned, and reduced trajectories (SMART) analysis was applied to compare the temporal metabolic
trajectories obtained for each animal at each dose level of the administered compounds. By day 4, the SMART trajectories for
allyl alcohol and hexachlorobutadiene had returned to predose levels indicating a recovery response, however, the high dose
SMART trajectories for para-aminophenol, puromycin aminonucleoside, sodium chromate, and galactosamine did not appear to return
to predose levels indicating a prolonged toxic effect. 相似文献
88.
Perovic D Tiffin P Douchkov D Bäumlein H Graner A 《Functional & integrative genomics》2007,7(2):169-179
Recent genomic projects reveal that about half of the gene repertoire in plant genomes is made up by multigene families. In
this paper, a set of structural and phylogenetic analyses have been applied to compare the differently sized nicotianamine
synthase (NAS) gene families in barley and rice. Nicotianamine acts as a chelator of iron and other heavy metals and plays
a key role in uptake, phloem transport and cytoplasmic distribution of iron, challenging efforts for the breeding of iron-efficient
crop plants. Nine barley NAS genes have been mapped, and co-linearity of flanking genes in barley and rice was determined.
The combined analyses reveal that the NAS multigene family members in barley originated through at least one duplication event
that occurred before the divergence of rice and barley. Additional duplications appear to have occurred within each of the
species. Although we detected no evidence for positive selection of recently duplicated genes within species, codon-based
tests revealed evidence for positive selection having contributed to the divergence of some amino acids. The integrated comparative
and phylogenetic analysis improved our current view of NAS gene family evolution, might facilitate the functional characterization
of individual members and is applicable to other multigene families.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
89.
Djordjevic DZ Cubrilo DG Barudzic NS Vuletic MS Zivkovic VI Nesic M Radovanovic D Djuric DM Jakovljevic VLj 《General physiology and biophysics》2012,31(2):211-219
The aims of our study were to assess the redox state of adolescent athletes and non-athletes both at rest and after acute exposure to physical load and to find relations between parameters of redox state and morphofunctional characteristics of subjects. 58 young handball players and 37 non-athletes were subjected to body composition analysis, measuring of maximal oxygen consumption and blood sampling immediately before and after a maximal progressive exercise test. At rest, athletes had significantly higher superoxide dismutase (SOD) and catalase (CAT) activity, higher levels of glutathione (GSH) and nitric oxide (NO) and lower levels of lipid peroxidation (TBARS) compared with non-athletes. A maximal exercise test induced statistically significant rise of superoxide anion radical (O2-), hydrogen peroxide (H2O2) and NO levels in non-athletes, while TBARS levels decreased. Athletes experienced the fall in NO levels and the fall in CAT activity. After exercise, athletes had significantly lower levels of O2- compared with non-athletes. Two way repeated measures ANOVA showed that the response of O2-, NO and TBARS to the exercise test was dependent on the sports engagement (training experience) of subjects. Significant correlations between morphofunctional and redox parameters were found. These results suggest that physical fitness affects redox homeostasis. 相似文献
90.
Rudenko IN Kaganovich A Hauser DN Beylina A Chia R Ding J Maric D Jaffe H Cookson MR 《The Biochemical journal》2012,446(1):99-111
Autosomal-dominant missense mutations in LRRK2 (leucine-rich repeat kinase 2) are a common genetic cause of PD (Parkinson's disease). LRRK2 is a multidomain protein with kinase and GTPase activities. Dominant mutations are found in the domains that have these two enzyme activities, including the common G2019S mutation that increases kinase activity 2-3-fold. However, there is also a genetic variant in some populations, G2385R, that lies in a C-terminal WD40 domain of LRRK2 and acts as a risk factor for PD. In the present study we show that the G2385R mutation causes a partial loss of the kinase function of LRRK2 and deletion of the C-terminus completely abolishes kinase activity. This effect is strong enough to overcome the kinase-activating effects of the G2019S mutation in the kinase domain. Hsp90 (heat-shock protein of 90 kDa) has an increased affinity for the G2385R variant compared with WT (wild-type) LRRK2, and inhibition of the chaperone binding combined with proteasome inhibition leads to association of mutant LRRK2 with high molecular mass native fractions that probably represent proteasome degradation pathways. The loss-of-function of G2385R correlates with several cellular phenotypes that have been proposed to be kinase-dependent. These results suggest that the C-terminus of LRRK2 plays an important role in maintaining enzymatic function of the protein and that G2385R may be associated with PD in a way that is different from kinase-activating mutations. These results may be important in understanding the differing mechanism(s) by which mutations in LRRK2 act and may also have implications for therapeutic strategies for PD. 相似文献