scholarly journals Selective Utilization of Benzimidazolyl-Norcobamides as Cofactors by the Tetrachloroethene Reductive Dehalogenase ofSulfurospirillum multivorans

2018 ◽  
Vol 200 (8) ◽  
Author(s):  
Sebastian Keller ◽  
Cindy Kunze ◽  
Martin Bommer ◽  
Christian Paetz ◽  
Riya C. Menezes ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Resonance Spectroscopy ◽  
General Effect ◽  
Content Type ◽  
Reductive Dehalogenase ◽  
Cofactor Binding ◽  
Lower Base ◽  
Negative Effect ◽  
First Time ◽  
Structural Insights

ABSTRACTThe organohalide-respiring bacteriumSulfurospirillum multivoransproduces a unique cobamide, namely, norpseudo-B12, which serves as cofactor of the tetrachloroethene (PCE) reductive dehalogenase (PceA). As previously reported, a replacement of the adeninyl moiety, the lower base of the cofactor, by exogenously applied 5,6-dimethylbenzimidazole led to inactive PceA. To explore the general effect of benzimidazoles on the PCE metabolism, the susceptibility of the organism for guided biosynthesis of various singly substituted benzimidazolyl-norcobamides was investigated, and their use as cofactor by PceA was analyzed. Exogenously applied 5-methylbenzimidazole (5-MeBza), 5-hydroxybenzimidazole (5-OHBza), and 5-methoxybenzimidazole (5-OMeBza) were found to be efficiently incorporated as lower bases into norcobamides (NCbas). Structural analysis of the NCbas by nuclear magnetic resonance spectroscopy uncovered a regioselectivity in the utilization of these precursors for NCba biosynthesis. When 5-MeBza was added, a mixture of 5-MeBza-norcobamide and 6-MeBza-norcobamide was formed, and the PceA enzyme activity was affected. In the presence of 5-OHBza, almost exclusively 6-OHBza-norcobamide was produced, while in the presence of 5-OMeBza, predominantly 5-OMeBza-norcobamide was detected. Both NCbas were incorporated into PceA, and no negative effect on the PceA activity was observed. In crystal structures of PceA, both NCbas were bound in the base-off mode with the 6-OHBza and 5-OMeBza lower bases accommodated by the same solvent-exposed hydrophilic pocket that harbors the adenine as the lower base of authentic norpseudo-B12. In this study, a selective production of different norcobamide isomers containing singly substituted benzimidazoles as lower bases is shown, and unique structural insights into their utilization as cofactors by a cobamide-containing enzyme are provided.IMPORTANCEGuided biosynthesis of norcobamides containing singly substituted benzimidazoles as lower bases by the organohalide-respiring epsilonproteobacteriumSulfurospirillum multivoransis reported. An unprecedented specificity in the formation of norcobamide isomers containing hydroxylated or methoxylated benzimidazoles was observed that implicated a strict regioselectivity of the norcobamide biosynthesis in the organism. In contrast to 5,6-dimethylbenzimidazolyl-norcobamide, the incorporation of singly substituted benzimidazolyl-norcobamides as a cofactor into the tetrachloroethene reductive dehalogenase was not impaired. The enzyme was found to be functional with different isomers and not limited to the use of adeninyl-norcobamide. Structural analysis of the enzyme equipped with either adeninyl- or benzimidazolyl-norcobamide cofactors visualized for the first time structurally different cobamides bound in base-off conformation to the cofactor-binding site of a cobamide-containing enzyme.

Insurance regulations, risk and performance in Ghana

2019 ◽  
Vol 28 (1) ◽  
pp. 74-96
Author(s):  
Baah Aye Kusi ◽  
Abdul Latif Alhassan ◽  
Daniel Ofori-Sasu ◽  
Rockson Sai
Keyword(s):  
Random Effect ◽  
Least Square ◽  
Insurance Market ◽  
Content Type ◽  
Ordinary Least Square ◽  
Negative Effect ◽  
And Performance ◽  
First Time

Purpose This study aims to examine the hypothesis that the effect of insurer risks on profitability is conditional on regulation, using two main regulatory directives in the Ghanaian insurance market as a case study. Design/methodology/approach This study used the robust ordinary least square and random effect techniques in a panel data of 30 insurers from 2009 to 2015 to test the research hypothesis. Findings The results suggest that regulations on no credit premium and required capital have insignificant effects on profitability of insurers. On the contrary, this study documents evidence that both policies mitigate the effect of underwriting risk on profitability and suggests that regulations significantly mitigate the negative effect of underwriting risk to improve profitability. Practical implications The finding suggests that policymakers and regulators must continue to initiate, design and model regulations such that they help tame risk to improve the performance of insurers in Ghana. Originality/value This study provides first-time evidence on the role of regulations in controlling risks in a developing insurance market.

The employment effects of offshoring: evidence from Korean manufacturing

2016 ◽  
Vol 20 (1) ◽  
pp. 21-34
Author(s):  
Sang-Chul Yoon
Keyword(s):  
Panel Data ◽  
Method Of Moments ◽  
Design Methodology ◽  
Generalized Method Of Moments ◽  
Employment Relationship ◽  
Content Type ◽  
Trade Specialization ◽  
Employment Effects ◽  
Negative Effect ◽  
First Time

Purpose – The purpose of this paper is to analyze the offshoring-employment relationship under globalization in Korean manufacturing for the period from 1998 to 2010 using industry-level panel data and Generalized Method of Moments. Design/methodology/approach – For the first time in the literature the type of trade specialization is taken into account, distinguishing manufacturing between export-specialized and import-specialized industries. Findings – There is evidence that materials and services offshoring have a significantly negative effect on employment in export-specialized industries. In contrast, there is a non-significant association in import-specialized industries. Research limitations/implications – These results may cast new light on the offshoring-employment relationship. Originality/value – Major contribution of this paper is that it sheds new light on the effect of offshoring on employment by distinguishing export-specialized industries from import-specialized industries.

Superionic Lithium Intercalation through 2 nm x 2 nm Columns in the Crystallographic Shear Phase Nb18W8O69

2019 ◽  
Author(s):  
Kent Griffith ◽  
Clare Grey
Keyword(s):  
High Performance ◽  
Rate Capability ◽  
Block Size ◽  
Lithium Intercalation ◽  
Resonance Spectroscopy ◽  
Complex Metal Oxides ◽  
Battery Electrode ◽  
Crystallographic Shear ◽  
Battery Material ◽  
First Time

Nb18W8O69 (9Nb2O5×8WO3) is the tungsten-rich end-member of the Wadsley–Roth crystallographic shear (cs) structures within the Nb2O5–WO3 series. It has the largest block size of any known, stable Wadsley–Roth phase, comprising 5 ´ 5 units of corner-shared MO6 octahedra between the shear planes, giving rise to 2 nm ´ 2 nm blocks. Rapid lithium intercalation is observed in this new candidate battery material and 7Li pulsed field gradient nuclear magnetic resonance spectroscopy – measured in a battery electrode for the first time at room temperature – reveals superionic lithium conductivity. In addition to its promising rate capability, Nb18W8O69 adds a piece to the larger picture of our understanding of high-performance Wadsley–Roth complex metal oxides.

Conference report: innovation, interaction … and a lot of data: first time reflections on Internet Librarian International, UK 2018

2019 ◽  
Vol 36 (2) ◽  
pp. 21-22
Author(s):  
Ray Harper
Keyword(s):  
Best Practice ◽  
New Technologies ◽  
Conference Report ◽  
Library Services ◽  
New Techniques ◽  
Content Type ◽  
Making A Difference ◽  
Analyse Data ◽  
Physical Spaces ◽  
First Time

Purpose The purpose of this paper is to summarise a number of presentations at Day 1 of the Internet Librarian International conference, London, UK (16 October 2018). This was the 20th conference in the series, and the three key themes included were the next-gen library and librarian; understanding users, usage and user experience; and inclusion and inspiration: libraries making a difference. Design/methodology/approach This paper reports from the viewpoint of a first-time attendee of the conference. This summarises the main issues raised by each presentation and draws out the key learning points for practical situations. Findings The conference covered a variety of practical ways in which libraries can use technology to support users and make decisions about services. These include developing interactive physical spaces which include augmented reality; introducing “chat-bots” to support users; using new techniques to analyse data; and piloting new ways to engage users (such as coding clubs). A key theme was how we use and harness data in a way that is ethical, effective and relevant to library services. Originality/value This conference focussed on practical examples of how library and information services across sectors and countries are innovating in a period of huge change. The conference gave delegates numerous useful ideas and examples of best practice and demonstrated the strength of the profession in adapting to new technologies and developments.

Interest rate option hedging portfolios without bank account

2019 ◽  
Vol 37 (1) ◽  
pp. 134-142
Author(s):  
Alberto Bueno-Guerrero
Keyword(s):  
Design Methodology ◽  
Contingent Claim ◽  
Necessary And Sufficient Condition ◽  
Barrier Option ◽  
Bank Account ◽  
Content Type ◽  
Option Hedging ◽  
Hedging Portfolio ◽  
Necessary And Sufficient ◽  
First Time

Purpose This paper aims to study the conditions for the hedging portfolio of any contingent claim on bonds to have no bank account part. Design/methodology/approach Hedging and Malliavin calculus techniques recently developed under a stochastic string framework are applied. Findings A necessary and sufficient condition for the hedging portfolio to have no bank account part is found. This condition is applied to a barrier option, and an example of a contingent claim whose hedging portfolio has a bank account part different from zero is provided. Originality/value To the best of the authors’ knowledge, this is the first time that this issue has been addressed in the literature.

The path of support-to-sales: mediating role of seller collaborative information exchange in social commerce

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Li Chen ◽  
Fengxia Zhu ◽  
Murali Mantrala
Keyword(s):  
Information Exchange ◽  
Instrumental Support ◽  
Trade Volume ◽  
Social Commerce ◽  
Content Type ◽  
Mediating Role ◽  
The Social ◽  
Source Data ◽  
Negative Effect

Purpose This paper aims to systematically investigate the direct and indirect effects of four types of support – peer instrumental support, peer emotional support, platform business support and platform communication support – on seller trade volume in social commerce. It also aims to uncover the path of support-to-sales of the seller from a platform perspective and provides a more complete picture of the social commerce phenomenon. Design/methodology/approach This paper uses multi-source data including primary survey data and secondary data on trade volume to test the hypotheses. PROCESS mediation model is used to analyze the multi-source data set. Findings This study finds that the positive effects of peer instrumental support, platform business support and platform communication support on seller trade volume are fully mediated by seller collaborative information exchange. Also, peer emotional support has a significant negative effect on seller trade volume and collaborative information exchange can serve as a buffer to mitigate the negative effect. Research limitations/implications The authors provide new insights into what types of support are or are not conducive to improving transaction volume of individual sellers and highlight the mediating role of seller information exchange in this value generation process in social commerce. These findings advance current knowledge of how seller interactions increase value in social commerce. The chosen research setting may limit the generalizability of the findings of this study. Practical implications This paper offers valuable implications for social commerce platforms on how to better serve their sellers to achieve high growth. Specifically, the findings suggest that platforms should encourage instrumental support and information exchange among peer sellers. In addition, platforms should expand seller support from a single-focus on sellers’ business to a dual-focus on both sellers’ business and socialization in social commerce. Originality/value This paper fulfills an identified need to study how sellers can better derive value from the social interactions and how social commerce platforms can effectively influence transactions, support sales and serve as a selling platform.

A “Learning from Action” workshop in Japan

2019 ◽  
Vol 40 (2) ◽  
pp. 77-83
Author(s):  
Robert Douglas Hinshelwood ◽  
Luca Mingarelli ◽  
Simona Masnata
Keyword(s):  
Far East ◽  
Opportunity To Learn ◽  
Content Type ◽  
Work Activities ◽  
Defensive Role ◽  
Feedback Data ◽  
Experiential Workshop ◽  
First Time ◽  
Practical Implications

Purpose Many people in severe mentally disturbed states do not use language or other symbolic media well or coherently. Therefore, the non-verbal medium needs to be understood by workers with such people. The “Learning from Action” experiential workshop was developed in order to provide an opportunity to learn about hidden messages in the relationships and roles occurring in activities. In August 2017, a workshop was run for the first time in Japan. The purpose of this paper is to report the experience and dynamics observed by the three consultants, who are here the authors of this paper. Design/methodology/approach After the workshop all the staff and members, including interpreters, were invited to give feedback. Findings Analysis of the feedback data showed certain important dynamics, concerning especially dependence, cultural defences and the defensive role of activity in a multicultural context. Research limitations/implications This is an initial experience to be followed up by later feedback and further workshops. Practical implications Workers awareness of non-verbal communication within the roles of work activities is a training possibility. It faces various resistances including the mental health assumptions of meaninglessness of any communication outside the verbal. Originality/value This is a method of training not widely used even in European countries, and is the first in a country in the far east.

Whirling in between the personal and the impersonal

2019 ◽  
Vol 25 (2) ◽  
pp. 257-284
Author(s):  
Armen E. Petrosyan
Keyword(s):  
Organization Theory ◽  
Conceptual Analysis ◽  
Essential Elements ◽  
Organizational Life ◽  
Critical Perspective ◽  
Content Type ◽  
Organizational Goals ◽  
Last Stage ◽  
First Time ◽  
Current Paradigm

Purpose The paper aims to present a systematic conceptual analysis of the problem of organizational goal and to reduce the insights into it provided by the main conceptions taken in their development from one to another, to break out of the ruling paradigm and outline a new solution. Design/methodology/approach The study has been carried out from the historical and critical perspective. Findings The paper discovers the logic of the evolution the approaches to organizational goals have undergone and portrays it in a matrix form in the heart of which is the “zigzag effect”: each posterior stage returns to the essential elements rejected by those preceding it, and the last stage, being diametrically opposite to the first, is, at that, as well as the latter, akin to the intermediate stages. The opportunities afforded by the current paradigm have been exhausted and it seems to run to an impasse. Instead, the author suggests a new frame of orientation: organizational goals are closely interknit with personal, but not reducible to them and bear fundamentally transpersonal character, while the mechanism of involving the preferences of individuals and groups in goal-setting is based on the self-contained interests of the organization they pertain to. Research limitations/implications The findings, conclusions and generalizations obtained can serve for a necessary ground to researchers getting deeper into the essence of what bonds organizational life and activity. Practical implications The material empowers practitioners to comprehend the difficulties of framing cohesive goal and find efficient ways to overcome them. It is of value also to the teachers seeking to present a more exact and elaborate view of teleological foundations of management and organization theory. Originality/value Both the conceptual analysis of the evolution of the approaches to organizational goals and the author’s exposition of its logic and vision of their nature are provided for the first time.

scholarly journals Structure and Molecular Recognition Mechanism of IMP-13 Metallo-β-Lactamase

2020 ◽  
Vol 64 (6) ◽  
Author(s):  
Charlotte A. Softley ◽  
Krzysztof M. Zak ◽  
Mark J. Bostock ◽  
Roberto Fino ◽  
Richard Xu Zhou ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Active Site ◽  
Rational Drug Design ◽  
Tryptophan Residue ◽  
Resonance Spectroscopy ◽  
Global Public Health ◽  
Recognition Mechanism ◽  
Gram Negative ◽  
Content Type ◽  
Locking Mechanism

ABSTRACT Multidrug resistance among Gram-negative bacteria is a major global public health threat. Metallo-β-lactamases (MBLs) target the most widely used antibiotic class, the β-lactams, including the most recent generation of carbapenems. Interspecies spread renders these enzymes a serious clinical threat, and there are no clinically available inhibitors. We present the crystal structures of IMP-13, a structurally uncharacterized MBL from the Gram-negative bacterium Pseudomonas aeruginosa found in clinical outbreaks globally, and characterize the binding using solution nuclear magnetic resonance spectroscopy and molecular dynamics simulations. The crystal structures of apo IMP-13 and IMP-13 bound to four clinically relevant carbapenem antibiotics (doripenem, ertapenem, imipenem, and meropenem) are presented. Active-site plasticity and the active-site loop, where a tryptophan residue stabilizes the antibiotic core scaffold, are essential to the substrate-binding mechanism. The conserved carbapenem scaffold plays the most significant role in IMP-13 binding, explaining the broad substrate specificity. The observed plasticity and substrate-locking mechanism provide opportunities for rational drug design of novel metallo-β-lactamase inhibitors, essential in the fight against antibiotic resistance.

The drivers of corporate governance disclosure: the case of Nifty 500 Index

2018 ◽  
Vol 60 (2) ◽  
pp. 681-700 ◽  
Author(s):  
Androniki Katarachia ◽  
Electra Pitoska ◽  
Grigoris Giannarakis ◽  
Elpida Poutoglidou
Keyword(s):  
Corporate Governance ◽  
Financial Leverage ◽  
Policy Makers ◽  
Content Type ◽  
Explanatory Variables ◽  
Size Number ◽  
Governance Practices ◽  
Board Director ◽  
First Time ◽  
Governance Disclosure

Purpose Based on agency theory, the purpose of this paper is to investigate the determinants on the dissemination level of corporate governance disclosure (CGD). Design/methodology/approach The sample of the study incorporates listed companies in Nifty 500 Index for the period 2009-2014. The Governance Disclosure Score calculated by Bloomberg is used as a proxy for the dissemination level of corporate governance information. In total, eight explanatory variables are uses, namely, board’s size, number of board meetings, CEO duality, presence of women on the board, company’s size, financial performance, Tobin’s Q ratio and financial leverage. Findings The results of study suggest a need for improvement in CGDs by Indian companies, as they fail to comply the majority of the proposed disclosure items. Furthermore, it is revealed that the number of board director, the value of company, the financial leverage and the presence of women affect negatively the dissemination level of corporate governance information. While, the size of company is the only determinant that positively affects the extent of CGD. Practical implications The results are valuable because they reveal the attributes that determines which companies needs less or extra monitoring by shareholders and investors regarding the applied corporate governance practices. In addition, the study can be valuable to policy makers responsible for the regulation of company’s accountability in relation to corporate governance practices. Originality/value The study extents previous studies by incorporating for the first time Bloomberg’s rating approach regarding the dissemination level of CGD in Indian context.

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