Transition States of Cisplatin Binding to Guanine and Adenine: ab initio Reactivity Study

2003 ◽  
Vol 68 (6) ◽  
pp. 1105-1118 ◽  
Author(s):  
Zdenek Chval ◽  
Miroslav Šíp
Keyword(s):  
Hydrogen Bonds ◽  
Dna Adducts ◽  
Binding Sites ◽  
Transition States ◽  
Activation Energies ◽  
Guanine And Adenine ◽  
Reactivity Study ◽  
First Time ◽  
Calculated Activation

Fully optimised HF and DFT transition states of cisplatin binding to adenine and guanine are presented for the first time. They have similar structure as the recently published transition states for cisplatin hydrolysis with the angle of about 70° between entering and leaving ligands and corresponding bonds prolonged up to 0.5 Å. Calculated activation energies are in the range of 10.5-18 kcal/mol. The lowest activation energies were found for the binding of cis-Pt[(NH3)2(H2O)(OH)]+ to guanine. The role of hydrogen bonds in recognition of binding sites, stabilisation of reactants and final yields of individual cisplatin-DNA adducts is discussed.

scholarly journals MicroRNA-24 Modulates Aflatoxin B1-Related Hepatocellular Carcinoma Prognosis and Tumorigenesis

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Yi-Xiao Liu ◽  
Xi-Dai Long ◽  
Zhi-Feng Xi ◽  
Yun Ma ◽  
Xiao-Ying Huang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Dna Adducts ◽  
Aflatoxin B1 ◽  
Tissue Samples ◽  
Noncancerous Tissue ◽  
Free Survival ◽  
Tumor Tissues ◽  
Neoplastic Process ◽  
First Time

MicroRNA-24 (miR-24) may be involved in neoplastic process; however, the role of this microRNA in the hepatocellular carcinoma (HCC) related to aflatoxin B1 (AFB1) has not been well elaborated. Here, we tested miR-24 expression in 207 pathology-diagnosed HCC cases from high AFB1 exposure areas and HCC cells. We found that miR-24 was upregulated in HCC tumor tissues relative to adjacent noncancerous tissue samples, and that the high expression of miR-24 was significantly correlated with larger tumor size, higher microvessel density, and tumor dedifferentiation. Additionally, this microRNA overexpression modified the recurrence-free survival (relative hazard ratio [HR], 4.75; 95% confidence interval [CI], 2.66–8.47) and overall survival (HR=3.58, 95% CI = 2.34–5.46) of HCC patients. Furthermore, we observed some evidence of joint effects between miR-24 and AFB1 exposure on HCC prognosis. Functionally, miR-24 overexpression progressed tumor cells proliferation, inhibited cell apoptosis, and developed the formation of AFB1-DNA adducts. These results indicate for the first time that miR-24 may modify AFB1-related HCC prognosis and tumorigenesis.

Die elektrische Leitfähigkeit hydratisierter Sulfate zwei- und dreiwertiger Kationen.

1976 ◽  
Vol 31 (10) ◽  
pp. 1313-1316
Author(s):  
Heinz P. Fritz ◽  
Dagmar Laschka
Keyword(s):  
Electrical Conductivity ◽  
Hydrogen Bonds ◽  
Proton Conductivity ◽  
Activation Energies ◽  
Charge Carriers ◽  
Elektrische Leitfähigkeit

The electrical conductivity of polycrystalline pellets of ZnSO4 · 7 H2O, MgSO4 · 7 H2O, CuSO4 · 5 H2O, KAl(SO4)2 · 12 H2O, NH4Al(SO4)2 · 12 H2O and KCr(SO4)2 · 12 H2O was measured. By coulometry the role of protons as charge carriers was determined. A correlation is given between the strength of hydrogen bonds and the activation energies for the proton conductivity.

scholarly journals An aniline dication-like transition state in the Bamberger rearrangement

2013 ◽  
Vol 9 ◽  
pp. 1073-1082 ◽  
Author(s):  
Shinichi Yamabe ◽  
Guixiang Zeng ◽  
Wei Guan ◽  
Shigeyoshi Sakaki
Keyword(s):  
Activation Energy ◽  
Dft Calculations ◽  
Transition State ◽  
Water Cluster ◽  
Transition States ◽  
Activation Energies ◽  
Nitrenium Ion ◽  
Proton Transfers ◽  
First Time

A Bamberger rearrangement of N-phenylhydroxylamine, Ph–N(OH)H, to p-aminophenol was investigated by DFT calculations for the first time. The nitrenium ion, C6H5–NH+, suggested and seemingly established as an intermediate was calculated to be absent owing to the high nucleophilicity of the water cluster around it. First, a reaction of the monoprotonated system, Ph–N(OH)H + H3O+(H2O) n (n = 4 and 14) was examined. However, the rate-determining transition states involving proton transfers were calculated to have much larger activation energies than the experimental one. Second, a reaction of the diprotonated system, Ph–N(OH)H + (H3O+)2(H2O)13, was traced. An activation energy similar to the experimental one was obtained. A new mechanism of the rearrangement including the aniline dication-like transition state was proposed.

scholarly journals The role of hydrogen bonds in diluted ethanol solutions of cyclohexane and dimethylformamide

2021 ◽  
pp. 44-47
Keyword(s):  
Hydrogen Bond ◽  
Refractive Index ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Hydrogen Bonds ◽  
Ethanol Solution ◽  
Pure Ethanol ◽  
First Time ◽  
Formed Hydrogen

The aim of this work is to determine molecular association in solutions of cyclohexane-ethanol and dimethylformamide-ethanol. The refractometric method and Fourier transform infrared spectroscopy used to determine the optical features of the concentration characteristics of diluted ethanol solutions of cyclohexane and dimethylformamide. It was found for the first time that at some concentrations the hydrogen bond is stronger than for a pure ethanol solution. The first maximum of the excess refractive index of solutions is formed at a concentration of 0.02 mole fraction of cyclohexane and dimethylformamide, which is in good correlation with IR spectroscopy, indicating the largest number of formed hydrogen bonds.

scholarly journals Mechanism of Base-Catalyzed Halogen Dance Reactions and the Role of Bromo-Bridged Transition States

2020 ◽  
Author(s):  
Nader Sakhaee ◽  
Yousef Fazaeli ◽  
Esmail Doustkhah ◽  
Sahar Sakhaee ◽  
Ahmad Takallou ◽  
...  
Keyword(s):  
Transition States ◽  
Basic Medium ◽  
New Ideas ◽  
To Come ◽  
First Time ◽  
Halogen Dance Reaction ◽  
Shed Light ◽  
Transformation Series ◽  
Aromatic Component

Base-catalyzed halogen dance reaction, has puzzled chemists ever since, to come up with new ideas regarding the mechanism of this beautiful chemical transformation. Series of fast metal-halogen exchanges are among the most recent mechanisms. Using DFT-Cam-B3LYP/ land2dz computations and focused on Halogen Dance (HD) reactions of bromobenzene derivatives, new bromo-bridged Transition States (TS) are proposed. These are then used to lay out 8 possible isomerization and 18 possible disproportionation paths. Mechanistic pathways were then analyzed based on TS’s energy and protonation/deprotonation steps to find the most suitable pathways. Overall pattern of these mechanisms draws for the first-time a cascade-like pattern for base-catalyzed halogen dance in its entirety. The present work shed light on a dynamic domino mechanism which dominates the realm of nonaqueous strongly basic medium reactions. Trends like these may well be a shared feature in base digestion of wood for its precious poly aromatic component like lignin.

scholarly journals Mapping the native interaction surfaces of PREP1 with PBX1 by cross-linking mass-spectrometry and mutagenesis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chiara Bruckmann ◽  
Simone Tamburri ◽  
Valentina De Lorenzi ◽  
Nunzianna Doti ◽  
Alessandra Monti ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Binding Sites ◽  
Transcriptional Activity ◽  
Tertiary Structure ◽  
Cross Linking ◽  
Interaction Sites ◽  
First Time

Abstract Both onco-suppressor PREP1 and the oncogene MEIS1 bind to PBX1. This interaction stabilizes the two proteins and allows their translocation into the nucleus and thus their transcriptional activity. Here, we have combined cross-linking mass-spectrometry and systematic mutagenesis to detail the binding geometry of the PBX1-PREP1 (and PBX1-MEIS1) complexes, under native in vivo conditions. The data confirm the existence of two distinct interaction sites within the PBC domain of PBX1 and unravel differences among the highly similar binding sites of MEIS1 and PREP1. The HR2 domain has a fundamental role in binding the PBC-B domain of PBX1 in both PREP1 and MEIS1. The HR1 domain of MEIS1, however, seem to play a less stringent role in PBX1 interaction with respect to that of PREP1. This difference is also reflected by the different binding affinity of the two proteins to PBX1. Although partial, this analysis provides for the first time some ideas on the tertiary structure of the complexes not available before. Moreover, the extensive mutagenic analysis of PREP1 identifies the role of individual hydrophobic HR1 and HR2 residues, both in vitro and in vivo.

scholarly journals MicroRNA-429 Modulates Hepatocellular Carcinoma Prognosis and Tumorigenesis

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Xiao-Ying Huang ◽  
Jin-Guang Yao ◽  
Hong-Dong Huang ◽  
Chao Wang ◽  
Yun Ma ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Overall Survival ◽  
Confidence Interval ◽  
Tumor Cells ◽  
Dna Adducts ◽  
Recurrence Free Survival ◽  
Free Survival ◽  
Tumor Tissues ◽  
First Time

MicroRNA-429 (miR-429) may modify the development and progression of cancers; however, the role of this microRNA in the hepatocellular carcinoma (HCC) has not been well elaborated. Here, we tested miR-429 expression in 138 pathology-diagnosed HCC cases and SMMC-7721 cells. We found that miR-429 was upregulated in HCC tumor tissues and that the high expression of miR-429 was significantly correlated with larger tumor size (odd ratio (OR), 2.70; 95% confidence interval (CI), 1.28–5.56) and higher aflatoxin B1-DNA adducts (OR = 3.13, 95% CI = 1.47–6.67). Furthermore, this microRNA overexpression modified the recurrence-free survival and overall survival of HCC patients. Functionally, miR-429 overexpression progressed tumor cells proliferation and inhibited cell apoptosis. These results indicate for the first time that miR-429 may modify HCC prognosis and tumorigenesis and may be a potential tumor therapeutic target.

Psychological Resilience Provides No Independent Protection From Suicidal Risk

Crisis ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 130-139 ◽  
Author(s):  
Danica W. Y. Liu ◽  
A. Kate Fairweather-Schmidt ◽  
Richard Burns ◽  
Rachel M. Roberts ◽  
Kaarin J. Anstey
Keyword(s):  
Risk Factors ◽  
Well Being ◽  
Current Status ◽  
Psychological Resilience ◽  
Cross Sectional ◽  
Life Project ◽  
Resilience Factors ◽  
First Time

Abstract. Background: Little is known about the role of resilience in the likelihood of suicidal ideation (SI) over time. Aims: We examined the association between resilience and SI in a young-adult cohort over 4 years. Our objectives were to determine whether resilience was associated with SI at follow-up or, conversely, whether SI was associated with lowered resilience at follow-up. Method: Participants were selected from the Personality and Total Health (PATH) Through Life Project from Canberra and Queanbeyan, Australia, aged 28–32 years at the first time point and 32–36 at the second. Multinomial, linear, and binary regression analyses explored the association between resilience and SI over two time points. Models were adjusted for suicidality risk factors. Results: While unadjusted analyses identified associations between resilience and SI, these effects were fully explained by the inclusion of other suicidality risk factors. Conclusion: Despite strong cross-sectional associations, resilience and SI appear to be unrelated in a longitudinal context, once risk/resilience factors are controlled for. As independent indicators of psychological well-being, suicidality and resilience are essential if current status is to be captured. However, the addition of other factors (e.g., support, mastery) makes this association tenuous. Consequently, resilience per se may not be protective of SI.

Synergetic Theory of Document in Evolution of Document Science

2018 ◽  
pp. 1060-1068
Author(s):  
Galina A. Dvoenosova ◽  
Keyword(s):  
Social Role ◽  
Scientific Study ◽  
Self Organization ◽  
Universal Theory ◽  
Social Self ◽  
Social Goal ◽  
The Social ◽  
Synergetic Theory ◽  
First Time

The article assesses synergetic theory of document as a new development in document science. In information society the social role of document grows, as information involves all members of society in the process of documentation. The transformation of document under the influence of modern information technologies increases its interest to representatives of different sciences. Interdisciplinary nature of document as an object of research leads to an ambiguous interpretation of its nature and social role. The article expresses and contends the author's views on this issue. In her opinion, social role of document is incidental to its being a main social tool regulating the life of civilized society. Thus, the study aims to create a scientific theory of document, explaining its nature and social role as a tool of social (goal-oriented) action and social self-organization. Substantiation of this idea is based on application of synergetics (i.e., universal theory of self-organization) to scientific study of document. In the synergetic paradigm, social and historical development is seen as the change of phases of chaos and order, and document is considered a main tool that regulates social relations. Unlike other theories of document, synergetic theory studies document not as a carrier and means of information transfer, but as a unique social phenomenon and universal social tool. For the first time, the study of document steps out of traditional frameworks of office, archive, and library. The document is placed on the scales with society as a global social system with its functional subsystems of politics, economy, culture, and personality. For the first time, the methods of social sciences and modern sociological theories are applied to scientific study of document. This methodology provided a basis for theoretical vindication of nature and social role of document as a tool of social (goal-oriented) action and social self-organization. The study frames a synergetic theory of document with methodological foundations and basic concepts, synergetic model of document, laws of development and effectiveness of document in the social continuum. At the present stage of development of science, it can be considered the highest form of theoretical knowledge of document and its scientific explanatory theory.

Physical Warmth Attenuates Ethnocentric Bias under Mortality Salience: An Embodied Terror Management Perspective

2020 ◽  
Author(s):  
Armand Chatard ◽  
Margaux Renoux ◽  
Jean Monéger ◽  
Leila Selimbegovic
Keyword(s):  
Mortality Salience ◽  
Terror Management ◽  
Negative Consequences ◽  
Defensive Reaction ◽  
Worldview Defense ◽  
Management Perspective ◽  
Physical Warmth ◽  
Alternative Means ◽  
First Time

Research indicates that individuals often deal with mortality salience by affirming beliefs in national or cultural superiority (worldview defense). Because worldview defense may be associated with negative consequences (discrimination), it is important to identify alternative means to deal with death-related thoughts. In line with an embodied terror management perspective, we evaluate for the first time the role of physical warmth in reducing defensive reaction to mortality salience. We predicted that, like social affiliation (social warmth), physical warmth could reduce worldview defense when mortality is salient. In this exploratory (preregistered) study, 202 French participants were primed with death-related thoughts, or an aversive control topic, in a heated room or a non-heated room. The main outcome was worldview defense (ethnocentric bias). We found no main effect of mortality salience on worldview defense. However, physical warmth reduced worldview defense when mortality was salient. Implications for an embodied terror management perspective are discussed.

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