First direct evidence of N-heterocyclic carbene in BMIm acetate ionic liquid. An electrochemical and chemical study on the role of temperature

Cyclic voltammetry provides the first direct evidence of N-­heterocyclic carbene (NHC) presence in neat 1-‐butyl-­3-­methylimidazolium acetate ionic liquid (BMImAcO) at 120°C. The NHC existence, proved by its oxidation current in cyclic voltammetry, was confirmed by the formation of a PhCHO-­NHC adduct in pure ionic liquid. The role of the temperature was considered

Electrogenerated N-Heterocyclic Carbene in Ionic Liquid: An Insight into the Mechanism of the Oxidative Esterification of Aromatic Aldehydes

An N-heterocyclic carbene (NHC), generated by cathodic reduction of BMImBF4, mediates the oxidative esterification of aromatic aldehydes with organic bromides in the corresponding ionic liquid as solvent. The product recovery by simple extractive work-up with diethyl ether allowed the ionic liquid to be recycled up to 9 times for subsequent electrolyses, with no significant loss in the product yield. The isolation of an intermediate, whose structure was confirmed by synthesis and transformation into the ester, provided the key for a mechanistic insight into the reaction. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Similarities and contrasts in the structure and function of the calcium transporter ATP2A1 and the copper transporter ATP7B

Ca2+ and Cu2+ ATPases are enzyme proteins that utilize ATP for active transport of Ca2+ or Cu2+ across intracellular or cellular membranes.1-4 These enzymes are referred to as P-type ATPases since they utilize ATP through formation of a phosphorylated intermediate (E-P) whose phosphorylation potential affects orientation and affinity of bound cations by means of extended conformational changes. Thereby specific cations are transported across membranes, forming transmembrane gradients in the case of Ca2+, or accepting Cu2+ from delivering proteins on one side of the membrane and releasing it to carrier proteins on the other side. Binding of Ca2+ or Cu2+ is required for enzyme activation and utilization of ATP by transfer of ATP terminal phosphate to a conserved aspartate residue. The ATPase protein is composed of a transmembrane region composed of helical segments and including the cation binding site (TMBS), and a cytosolic headpiece with three domains (A, N and P) containing the catalytic and phosphorylation site. The number of helical segments and the cytosolic headpieces present significant differences in the two enzymes. In addition, details of transmembrane cation extrusion are different. The Ca2+ and Cu2+ ATPase sustain vital physiological functions, such as muscle contraction and relaxation, activation of several cellular enzymes, and elimination of excess cation concentrations. A historic review of studies on chemical and physiological mechanisms of the Ca2+ and Cu2+ ATPase is presented

An innovative strategy for electrochemically-promoted addition reactions

A new strategy based on the catalytic release of the supporting electrolyte agent in the electrolysis medium proved to be effective for the direct electroactivation of suitable C–H acid-containing compounds vs. catalytic addition processes, under solvent-free conditions

Reaction Cycle of Thermotoga maritima Copper ATPase and Conformational Characterization of Catalytically Deficient Mutants†

ABSTRACT: Copper transport ATPases sustain important roles in homeostasis of heavy metals and delivery of copper to metalloenzymes. The copper transport ATPase from Thermotoga maritima (CopA) provides a useful system for mechanistic studies, due to its heterologous expression and stability. Its sequence comprises 726 amino acids, including the N-terminal metal binding domain (NMBD), three catalytic domains (A, N, and P), and a copper transport domain formed by eight helices, including the transmembrane metal binding site (TMBS). We performed functional characterization and conformational analysis by proteolytic digestion of WT and mutated (NMBD deletion or mutation) T. maritima CopA, comparing it with Archaeoglobus fulgidus CopA and Ca2+ ATPase. A specific feature of T. maritima CopA is ATP utilization in the absence of copper, to form a low-turnover phosphoenzyme intermediate, with a conformation similar to that obtained by phosphorylation with Pi or phosphate analogues. On the other hand, formation of an activated state requires copper binding to both NMBD and TMBS, with consequent conformational changes involving the NMBD and A domain. Proteolytic digestion analysis demonstrates A domain movements similar to those of other P-type ATPases to place the conserved TGES motif in the optimal position for catalytic assistance.We also studied anH479Qmutation (analogous to one of human copper ATPase ATP7B in Wilson disease) that inhibits ATPase activity. We found that, in spite of the H479Q mutation within th

The role of power in financial statement fraud schemes

In this paper, we investigate a large-scale financial statement fraud to better understand the process by which individuals are recruited to participate in financial statement fraud schemes. The case reveals that perpetrators often use power to recruit others to participate in fraudulent acts. To illustrate how power is used, we propose a model, based upon the classical French and Raven taxonomy of power, that explains how one individual influences another individual to participate in financial statement fraud. We also provide propositions for future research

How prosocial actors use power hierarchies to build moral reputation

Power hierarchies are ubiquitous, emerging formally and informally, in both personal and professional contexts. When prosocial acts are offered within power hierarchies, there is a widespread belief that people who choose lower-power beneficiaries are altruistically motivated, and that those who choose higher-power beneficiaries hold a self-interested motive to ingratiate. In contrast, the current research empirically demonstrates that people can also choose lower-power beneficiaries for self-interested reasons – namely, to bolster their own moral reputation in the group. Across three pre-registered studies, involving different contexts and types of prosocial behavior, and including real financial incentives, we demonstrate that people are more likely to choose lower-power beneficiaries when reputation concerns are more salient. We also provide evidence of the mechanism underlying this pattern: people believe that choosing a lower-power beneficiary more effectively signals their own moral character