scholarly journals Recombinant two-iron rubredoxin of Pseudomonas oleovorans: overexpression, purification and characterization by optical, CD and 113Cd NMR spectroscopies

1997 ◽  
Vol 328 (1) ◽  
pp. 131-136 ◽  
Author(s):  
Ho Joon LEE ◽  
Lu-Yun LIAN ◽  
S. Nigel SCRUTTON
Keyword(s):  
Chemical Exchange ◽  
Chemical Shifts ◽  
Pseudomonas Oleovorans ◽  
Redox Active ◽  
Step Procedure ◽  
High Frequency Shift ◽  
The Difference ◽  
Ferrous Ammonium ◽  
High Level ◽  
Difference Absorption

The gene (alk G) encoding the two-iron rubredoxin of Pseudomonas oleovorans was amplified from genomic DNA by PCR and subcloned into the expression vector pKK223-3. The vector directed the high-level production of rubredoxin in Escherichia coli. A simple three-step procedure was used to purify recombinant rubredoxin in the 1Fe form. 1Fe-rubredoxin was readily converted to the 2Fe, apoprotein and cadmium forms after precipitation with trichloroacetic acid and resolubilization in the presence or absence of ferrous ammonium sulphate or CdCl2 respectively. Recombinant 1Fe and 2Fe rubredoxins are redox-active and able to transfer electrons from reduced spinach ferredoxin reductase to cytochrome c. The absorption spectrum and dichroic features of the CD spectrum for the cadmium-substituted protein are similar to those reported for cadmium-substituted Desulfovibrio gigas rubredoxin [Henehan, Poutney, Zerbe and Vasak (1993) Protein Sci. 2, 1756-1764]. Difference absorption spectroscopy of cadmium-substituted rubredoxin revealed the presence of four Gaussian-resolved maxima at 207, 228, 241 and 280 nm; the 241 nm band is attributable, from J⊘rgensen's electronegativity theory, to a CysS-CdII charge-transfer excitation. The 113Cd NMR spectrum of the 113Cd-substituted rubredoxin contains two 113Cd resonances with chemical shifts located at 732.3 and 730 p.p.m. The broader linewidth and high frequency shift of the resonance at 730 p.p.m. indicates that the Cd2+ ion is undergoing chemical exchange and, consistent with the difference absorption spectra, is bound less tightly than the Cd2+ ion, giving rise to the chemical shift at 732.3 p.p.m.

Two-iron rubredoxin of Pseudomonas oleovorans: production, stability and characterization of the individual iron-binding domains by optical, CD and NMR spectroscopies

2001 ◽  
Vol 354 (1) ◽  
pp. 89-98 ◽  
Author(s):  
Ashlee PERRY ◽  
Lu-Yun LIAN ◽  
Nigel S. SCRUTTON
Keyword(s):  
Simple Procedure ◽  
Factor Xa ◽  
Pseudomonas Oleovorans ◽  
Terminal Domain ◽  
Binding Domains ◽  
Redox Active ◽  
Charge Transfer Excitation ◽  
The Individual ◽  
High Level ◽  
Difference Absorption

A minigene encoding the C-terminal domain of the 2Fe rubredoxin of Pseudomonas oleovorans was created from the parental alk G gene contained in the expression plasmid pKK223-3. The vector directed the high-level production of the C-terminal domain of this rubredoxin; a simple procedure was used to purify the recombinant domain in the 1Fe form. The 1Fe form of the C-terminal domain was readily converted into the apoprotein and cadmium forms after precipitation with trichloroacetic acid and resolubilization in the presence or absence of cadmium chloride respectively. In steady-state assays, the recombinant 1Fe C-terminal domain is redox-active and able to transfer electrons from reduced rubredoxin reductase to cytochrome c. The absorption spectrum and dichroic features of the CD spectrum for the iron- and cadmium-substituted C-terminal domain are similar to those reported for the iron- and cadmium-substituted Desulfovibrio gigas rubredoxin [Henehen, Pountney, Zerbe and Vasak (1993) Protein Sci. 2, 1756–1764]. Difference absorption spectroscopy of the cadmium-substituted C-terminal domain revealed the presence of four Gaussian-resolved maxima at 202, 225, 240 and 276nm; from J⊘rgensen's electronegativity theory, the 240nm band is attributable to a CysS-Cd(II) charge-transfer excitation. Attempts to express the N-terminal domain of the 2Fe rubredoxin directly from a minigene were unsuccessful. However, the N-terminal domain was isolated through cleavage of an engineered 2Fe rubredoxin in which a factor Xa proteolysis site had been introduced into the putative interdomain linker. The N-terminal domain is characterized by absorption spectra typical of the 1Fe rubredoxins. The domain is folded as determined by CD and NMR spectroscopies and is redox-active. However, the N-terminal domain is less stable than the isolated C-terminal domain, a finding consistent with the known properties of the full-length 2Fe and cadmium-substituted Ps. oleovorans rubredoxin.

Difference of [Ca2+]i Movements in Platelets Stimulated by Thrombin and TRAP: the Involvement of αIIbβ3-Mediated TXA2 Synthesis

1998 ◽  
Vol 79 (06) ◽  
pp. 1184-1190 ◽  
Author(s):  
Yoshiaki Tomiyama ◽  
Shigenori Honda ◽  
Kayoko Senzaki ◽  
Akito Tanaka ◽  
Mitsuru Okubo ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Fibrinogen Binding ◽  
Adp Release ◽  
The Difference ◽  
Txa2 Receptor Antagonist ◽  
High Level ◽  
Inhibition Studies ◽  
Peak Increase ◽  
Second Peak ◽  
Assay Conditions

SummaryThis study investigated the difference of [Ca2+]i movement in platelets in response to thrombin and TRAP. The involvement of αIIbβ3 in this signaling was also studied. Stimulation of platelets with thrombin at 0.03 U/ml caused platelet aggregation and a two-peak increase in [Ca2+]i. The second peak of [Ca2+]i, but not the first peak was abolished by the inhibition of platelet aggregation with αIIbβ3 antagonists or by scavenging endogenous ADP with apyrase. A cyclooxygenase inhibitor, aspirin, and a TXA2 receptor antagonist, BM13505, also abolished the second peak of [Ca2+]i but not the first peak, although these regents did not inhibit aggregation. Under the same assay conditions, measurement of TXB2 demonstrated that αIIbβ3 antagonists and aspirin almost completely inhibited the production of TXB2. In contrast to thrombin-stimulation, TRAP caused only a single peak of [Ca2+]i even in the presence of platelet aggregation, and a high level of [Ca2+]i increase was needed for the induction of platelet aggregation. The inhibition of aggregation with αIIbβ3 antagonists had no effect on [Ca2+]i change and TXB2 production induced by TRAP. Inhibition studies using anti-GPIb antibodies suggested that GPIb may be involved in the thrombin response, but not in the TRAP. Our findings suggest that low dose thrombin causes a different [Ca2+]i response and TXA2 producing signal from TRAP. Endogenous ADP release and fibrinogen binding to αIIbβ3 are responsible for the synthesis of TXA2 which results in the induction of the second peak of [Ca2+]i in low thrombin- but not TRAP-stimulated platelets.

ATTITUDE TO OPEN ACCESS IN RUSSIAN SCHOLARLY COMMUNITY: 2018. SURVEY RESULTS AND ANALYSIS

2018 ◽  
Vol 1 (1) ◽  
pp. 6-21 ◽  
Author(s):  
I. K. Razumova ◽  
N. N. Litvinova ◽  
M. E. Shvartsman ◽  
A. Yu. Kuznetsov
Keyword(s):  
Open Access ◽  
Open Access Publishing ◽  
Scholarly Community ◽  
Research Areas ◽  
Survey Results ◽  
The Difference ◽  
Policies And Programs ◽  
The Uk ◽  
High Level ◽  
Access Policies

Introduction. The paper presents survey results on the awareness towards and practice of Open Access scholarly publishing among Russian academics.Materials and Methods. We employed methods of statistical analysis of survey results. Materials comprise results of data processing of Russian survey conducted in 2018 and published results of the latest international surveys. The survey comprised 1383 respondents from 182 organizations. We performed comparative studies of the responses from academics and research institutions as well as different research areas. The study compares results obtained in Russia with the recently published results of surveys conducted in the United Kingdom and Europe.Results. Our findings show that 95% of Russian respondents support open access, 94% agree to post their publications in open repositories and 75% have experience in open access publishing. We did not find any difference in the awareness and attitude towards open access among seven reference groups. Our analysis revealed the difference in the structure of open access publications of the authors from universities and research institutes. Discussion andConclusions. Results reveal a high level of awareness and support to open access and succeful practice in the open access publications in the Russian scholarly community. The results for Russia demonstrate close similarity with the results of the UK academics. The governmental open access policies and programs would foster the practical realization of the open access in Russia.

Quantitative indicators of air traffic controllers’ attitude to the danger of errors

2020 ◽  
pp. 68-78
Author(s):  
O. M. Reva ◽  
V. V. Kamyshin ◽  
S. P. Borsuk ◽  
V. A. Shulhin ◽  
A. V. Nevynitsyn
Keyword(s):  
Human Factor ◽  
Differential Method ◽  
Air Traffic ◽  
Professional Activity ◽  
Aviation Accidents ◽  
Air Traffic Controllers ◽  
The Difference ◽  
Level Of Significance ◽  
The Individual ◽  
High Level

The negative and persistent impact of the human factor on the statistics of aviation accidents and serious incidents makes proactive studies of the attitude of “front line” aviation operators (air traffic controllers, flight crewmembers) to dangerous actions or professional conditions as a key component of the current paradigm of ICAO safety concept. This “attitude” is determined through the indicators of the influence of the human factor on decision-making, which also include the systems of preferences of air traffic controllers on the indicators and characteristics of professional activity, illustrating both the individual perception of potential risks and dangers, and the peculiarities of generalized group thinking that have developed in a particular society. Preference systems are an ordered (ranked) series of n = 21 errors: from the most dangerous to the least dangerous and characterize only the danger preference of one error over another. The degree of this preference is determined only by the difference in the ranks of the errors and does not answer the question of how much time one error is more dangerous in relation to another. The differential method for identifying the comparative danger of errors, as well as the multistep technology for identifying and filtering out marginal opinions were applied. From the initial sample of m = 37 professional air traffic controllers, two subgroups mB=20 and mG=7 people were identified with statisti-cally significant at a high level of significance within the group consistency of opinions a = 1%. Nonpara-metric optimization of the corresponding group preference systems resulted in Kemeny’s medians, in which the related (middle) ranks were missing. Based on these medians, weighted coefficients of error hazards were determined by the mathematical prioritization method. It is substantiated that with the ac-cepted accuracy of calculations, the results obtained at the second iteration of this method are more ac-ceptable. The values of the error hazard coefficients, together with their ranks established in the preference systems, allow a more complete quantitative and qualitative analysis of the attitude of both individual air traffic controllers and their professional groups to hazardous actions or conditions.

Synthesis and characterization of a series of 1-methyl-4-[2-aryl-1-diazenyl]piperazines and a series of ethyl 4-[2-aryl-1-diazenyl]-1-piperazinecarboxylates

2004 ◽  
Vol 82 (8) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vanessa Renée Little ◽  
Keith Vaughan
Keyword(s):  
Free Energy ◽  
Chemical Shifts ◽  
Linear Free Energy Relationship ◽  
Piperazine Ring ◽  
Linear Free Energy ◽  
In Series ◽  
Methylene Groups ◽  
Diazonium Coupling ◽  
The Difference

1-Methylpiperazine was coupled with a series of diazonium salts to afford the 1-methyl-4-[2-aryl-1-diazenyl]piperazines (2), a new series of triazenes, which have been characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and elemental analysis. Assignment of the chemical shifts to specific protons and carbons in the piperazine ring was facilitated by comparison with the chemical shifts in the model compounds piperazine and 1-methylpiperazine and by a HETCOR experiment with the p-tolyl derivative (2i). A DEPT experiment with 1-methylpiperazine (6) was necessary to distinguish the methyl and methylene groups in 6, and a HETCOR spectrum of 6 enabled the correlation of proton and carbon chemical shifts. Line broadening of the signals from the ring methylene protons is attributed to restricted rotation around the N2-N3 bond of the triazene moiety in 2. The second series of triazenes, the ethyl 4-[2-phenyl-1-diazenyl]-1-piperazinecarboxylates (3), have been prepared by similar diazonium coupling to ethyl 1-piperazinecarboxylate and were similarly characterized. The chemical shifts of the piperazine ring protons are much closer together in series 3 than in series 2, resulting in distortion of the multiplets for these methylenes. It was noticed that the difference between these chemical shifts in 3 exhibited a linear free energy relationship with the Hammett substituent constants for the substituents in the aryl ring. Key words: triazene, piperazine, diazonium coupling, NMR, HETCOR, linear free energy relationship.

scholarly journals A Modified KNN Algorithm for High-Performance Computing on FPGA of Real-Time m-QAM Demodulators

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 627
Author(s):  
David Marquez-Viloria ◽  
Luis Castano-Londono ◽  
Neil Guerrero-Gonzalez
Keyword(s):  
Real Time ◽  
High Performance ◽  
Interference Mitigation ◽  
Parallel Implementation ◽  
Computational Time ◽  
Successful Implementation ◽  
Interchannel Interference ◽  
The Difference ◽  
High Level ◽  
Performance Computing

A methodology for scalable and concurrent real-time implementation of highly recurrent algorithms is presented and experimentally validated using the AWS-FPGA. This paper presents a parallel implementation of a KNN algorithm focused on the m-QAM demodulators using high-level synthesis for fast prototyping, parameterization, and scalability of the design. The proposed design shows the successful implementation of the KNN algorithm for interchannel interference mitigation in a 3 × 16 Gbaud 16-QAM Nyquist WDM system. Additionally, we present a modified version of the KNN algorithm in which comparisons among data symbols are reduced by identifying the closest neighbor using the rule of the 8-connected clusters used for image processing. Real-time implementation of the modified KNN on a Xilinx Virtex UltraScale+ VU9P AWS-FPGA board was compared with the results obtained in previous work using the same data from the same experimental setup but offline DSP using Matlab. The results show that the difference is negligible below FEC limit. Additionally, the modified KNN shows a reduction of operations from 43 percent to 75 percent, depending on the symbol’s position in the constellation, achieving a reduction 47.25% reduction in total computational time for 100 K input symbols processed on 20 parallel cores compared to the KNN algorithm.

scholarly journals E-learning-Oriented Software Architecture Design and Case Study

2015 ◽  
Vol 10 (4) ◽  
pp. 59
Author(s):  
Peng Lu ◽  
Xiao Cong ◽  
Dongdai Zhou
Keyword(s):  
Software Architecture ◽  
Building Blocks ◽  
Domain Model ◽  
Learning System ◽  
Application Framework ◽  
Component Library ◽  
E Learning ◽  
The Difference ◽  
High Level

Nowadays, E-learning system has been widely applied to practical teaching. It was favored by people for its characterized course arrangement and flexible learning schedule. However, the system does have some problems in the process of application such as the functions of single software are not diversified enough to satisfy the requirements in teaching completely. In order to cater more applications in the teaching process, it is necessary to integrate functions from different systems. But the difference in developing techniques and the inflexibility in design makes it difficult to implement. The major reason of these problems is the lack of fine software architecture. In this article, we build domain model and component model of E-learning system and components integration method on the basis of WebService. And we proposed an abstract framework of E-learning which could express the semantic relationship among components and realize high level reusable on the basis of informationized teaching mode. On this foundation, we form an E-learning oriented layering software architecture contain component library layer, application framework layer and application layer. Moreover, the system contains layer division multiplexing and was not built upon developing language and tools. Under the help of the software architecture, we could build characterized E-learning system flexibly like building blocks through framework selection, component assembling and replacement. In addition, we exemplify how to build concrete E-learning system on the basis of this software architecture.

scholarly journals Has the Propensity to Pay Dividends Declined? Evidence from the US Banking Sector

2021 ◽  
Vol 14 (3) ◽  
pp. 103
Author(s):  
Shaojie Lai ◽  
Qing Wang ◽  
Jiangze Du ◽  
Shuwen Pi
Keyword(s):  
Banking Sector ◽  
Logit Models ◽  
Sample Period ◽  
Financial Firms ◽  
The Us ◽  
The Difference ◽  
High Level ◽  
Propensity To Pay ◽  
Financial Firm ◽  
Very High

This article examines the propensity to pay dividends in the U.S banking sector during 1973–2014. Although the propensity to pay dividends has been declining over the 52 years of our sample period, banks are consistently more likely to pay dividends than non-financial firms. Using the coefficients from logit models estimated early in the sample period to forecast the percentage of dividend payers in each subsequent year, we conclude that there has been a decline in the likelihood of paying dividends in the banking sector. However, the decline started from a very high level as compared to that of the non-banking sectors. In addition, the variables taken from the non-financial firm literature do not explain the difference between the actual and expected percentage of dividend payers in the banking sector. We also conduct exploratory analyses with bank-specific variables. Although newly included variables are significantly related to the likelihood of paying dividends, they do not explain the declining propensity to pay dividends in the banking sector.

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