Theoretical study on the activation mechanism of AMP-kinase by means of Molecular Dynamics Simulations

Mammalian AMP-activated protein kinase (AMPK) is a Ser108/Thr132 heterotrimeric enzyme complex (one catalytic subunit a and two regulatory subunits b and g) with a key role as sensor in the cellular energy homeostasis. This function confers AMPK a major role in numerous metabolic disorders, such as type 2 diabetes, obesity and cancer, and explains the progressive interest as a therapeutic target. AMPK is regulated by several mechanisms including indirect and direct activators, which show clear specificity by a particular subunit. We have carried out a series of molecular dynamic simulations of the apo and holo forms of AMPK to gain insight into the mechanism of AMPK activation

Theoretical study on the activation mechanism of AMP-kinase by means of Molecular Dynamics Simulations

Mammalian AMP-activated protein kinase (AMPK) is a Ser108/Thr132 heterotrimeric enzyme complex (one catalytic subunit a and two regulatory subunits b and g) with a key role as sensor in the cellular energy homeostasis. This function confers AMPK a major role in numerous metabolic disorders, such as type 2 diabetes, obesity and cancer, and explains the progressive interest as a therapeutic target. AMPK is regulated by several mechanisms including indirect and direct activators, which show clear specificity by a particular subunit. We have carried out a series of molecular dynamic simulations of the apo and holo forms of AMPK to gain insight into the mechanism of AMPK activation

Electrostatic Tuning of the Ligand Binding Mechanism by Glu27 in Nitrophorin 7.

Nitrophorins (NP) 1-7 are NO-carrying heme proteins found in the saliva of the blood-sucking insect Rhodnius prolixus. The isoform NP7 displays peculiar properties, such as an abnormally high isoelectric point, the ability to bind negatively charged membranes, and a strong pH sensitivity of NO affinity. A unique trait of NP7 is the presence of Glu in position 27, which is occupied by Val in other NPs. Glu27 appears to be important for tuning the heme properties, but its influence on the pH-dependent NO release mechanism, which is assisted by a conformational change in the AB loop, remains unexplored. Here, in order to gain insight into the functional role of Glu27, we examine the effect of Glu27 → Val and Glu27 → Gln mutations on the ligand binding kinetics using CO as a model. The results reveal that annihilation of the negative charge of Glu27 upon mutation reduces the pH sensitivity of the ligand binding rate, a process that in turn depends on the ionization of Asp32. We propose that Glu27 exerts a through-space electrostatic action on Asp32, which shifts the pKa of the latter amino acid towards more acidic values thus reducing the pH sensitivity of the transition between open and closed states

Incorporation of fungal cellulases in bacterial minicellulosomes yields viable, synergistically acting celluloytic complexes

Artificial designer minicellulosomes comprise a chimeric scaffoldin that displays an optional cellulose-binding module (CBM) and bacterial cohesins from divergent species which bind strongly to enzymes engineered to bear complementary dockerins. Incorporation of cellulosomal cellulases from Clostridium cellulolyticum into minicellulosomes leads to artificial complexes with enhanced activity on crystalline cellulose, due to enzyme proximity and substrate targeting induced by the scaffoldin-borne CBM. In the present study, a bacterial dockerin was appended to the family 6 fungal cellulase Cel6A, produced by Neocallimastix patriciarum, for subsequent incorporation into minicellulosomes in combination with various cellulosomal cellulases from C. cellulolyticum. The binding of the fungal Cel6A with a bacterial family 5 endoglucanase onto chimeric miniscaffoldins had no impact on their activity toward crystalline cellulose. Replacement of the bacterial family 5 enzyme with homologous endoglucanase Cel5D from N. patriciarum bearing a clostridial dockerin gave similar results. In contrast, enzyme pairs comprising the fungal Cel6A and bacterial family 9 endoglucanases were substantially stimulated (up to 2.6-fold) by complexation on chimeric scaffoldins, compared to the free-enzyme system. Incorporation of enzyme pairs including Cel6A and a processive bacterial cellulase generally induced lower stimulation levels. Enhanced activity on crystalline cellulose appeared to result from either proximity or CBM effects alone but never from both simultaneously, unlike minicellulosomes composed exclusively of bacterial cellulases. The present study is the first demonstration that viable designer minicellulosomes can be produced that include (i) free (noncellulosomal) enzymes, (ii) fungal enzymes combined with bacterial enzymes, and (iii) a type (family 6) of cellulase never known to occur in natural cellulosomes

Towards a Sustainable Governance of Information Systems: Devising a Maturity Assessment Tool of Eco-Responsibility Inspired by the Balanced Scorecard

Part 3: Section 2: Sustainable and Responsible InnovationInternational audienceThe assessment of the maturity of Information System (IS) regarding its contribution to corporate social responsibility policy is considered as a stake for organizations. However, few research efforts have been dedicated to this evaluation and even less to the elaboration of a management tool. This paper adopts an engineering perspective to develop a performance assessment approach in this field. Theoretically, this communication (1) mobilizes the methodology of engineering research to build a measurement system of the IS maturity in relation to the economic, social and environmental performance, (2) extends the researches about the sustainable balanced scorecard (SBSC) to the field of IS governance. Practically, this study provides organizations with a global approach to this complex phenomenon as well as a guide to assess it. The originality of this research lies in the application of the conceptual framework of the SBSC to a new research domain

Continuum solvation models: Dissecting the free energy of solvation

The most usual self-consistent reaction field (SCRF) continuum models for the description of solvation within the quantum mechanical (QM) framework are reviewed, trying to emphasize their common roots as well as the inherent approximations assumed in the calculation of the free energy of solvation. Particular attention is also paid to the specific features involved in the development of current state-of-the-art QM SCRF continuum models. This is used to discuss the need to maintain a close correspondence between each SCRF formalism and the specific details entailing its parametrization, as well as the need to be cautious in analyzing the balance between electrostatic and non-electrostatic contributions to the solvation free energy between different SCRF models. Finally, special emphasis is given to the post-processing of the free energy of solvation to derive parameters providing a compact picture of the ability of a molecule to interact with different solvents, which can be of particular interest in biopharmaceutical studies

Children’s first experience of taking anabolic-androgenic steroids can occur before their 10th birthday: a systematic review identifying 9 factors that predict doping among young people

Taking performance-enhancing drugs (PEDs) can cause serious and irreversible health consequences, which can ultimately lead to premature death. Some young people may take PEDs without fully understanding the ramifications of their actions or based on the advice from others. The purpose of this systematic review was to identify the main factors that predicted doping among young people. The literature was systematically reviewed using search engines, manually searching specialist journals, and pearl growing. Fifty-two studies, which included 187,288 young people aged between 10 and 21 years of age, 883 parents of adolescent athletes, and 11 adult coaches, who were interviewed regarding young athletes, were included in this review. Nine factors predicted doping among young people: gender; age; sports participation; sport type; psychological variables; entourage; ethnicity; nutritional supplements’ and health harming behaviors. In regards to psychological variables, 22 different constructs were associated with doping among young people. Some psychological constructs were negatively associated with doping (e.g., self-esteem, resisting social pressure, and perfectionist strivings), whereas other were positively associated with doping (e.g., suicide risk, anticipated regret, and aggression). Policy makers and National Anti-Doping Organisations could use these findings to help identify athletes who are more at risk of doping and then expose these individuals to anti-doping education. Based on the current findings, it also appears that education programs should commence at the onset of adolescence or even late childhood, due to the young age in which some individuals start doping

A feasibility randomised controlled trial examining the effects of the Anti-Doping Values in Coach Education (ADVICE) mobile application on doping knowledge and attitudes towards doping among grassroots coaches

Objectives: Sports coaches are influential in whether athletes dope, but receive very little anti-doping education, particularly within entry level coaching qualifications. We tested the feasibility of an anti-doping intervention, delivered via a mobile application, which was designed to increase coaches’ knowledge of doping and to reduce favourable doping attitudes. Methods: A two-arm randomised controlled trial, with grassroots coaches who coach young amateur athletes aged between 14 and 18 years of age, was conducted. The Anti-Doping Values in Coach Education (ADVICE) mobile application included modules on fair play, substances, nutritional supplements, rules, and leadership. The primary outcome was the change in doping knowledge, 6 weeks after receiving the mobile application. The secondary outcome was changes in doping attitudes. Results: Grassroots coaches (n=200; aged between 18- and 71-years-old, with between 1- and 42-years coaching experience) from 29 different countries completed baseline assessments, and 85 completed follow-up assessments, and were included in mixed analysis of variance analyses. The intervention increased coaches’ knowledge about doping and also reduced favourable doping attitudes in the experimental arm. Conclusion: The ADVICE mobile application is a feasible method for delivering and increasing grassroots coaches’ knowledge of banned substances and the potential side effects of doping. Mobile application-based resources could facilitate a much wider dissemination of anti-doping education