Molecular shielding of electric field complex dissociation

From Acid Activation Mechanisms of Proton Conduction to Design of Inhibitors of the M2 Proton Channel of Influenza A Virus

With an estimated 1 billion people affected across the globe, influenza is one of the most serious health concerns worldwide. Therapeutic treatments have encompassed a number of key functional viral proteins, mainly focused on the M2 proton channel and neuraminidase. This review highlights the efforts spent in targeting the M2 proton channel, which mediates the proton transport toward the interior of the viral particle as a preliminary step leading to the release of the fusion peptide in hemagglutinin and the fusion of the viral and endosomal membranes. Besides the structural and mechanistic aspects of the M2 proton channel, attention is paid to the challenges posed by the development of efficient small molecule inhibitors and the evolution toward novel ligands and scaffolds motivated by the emergence of resistant strains.

Co-Evolution of Opioid and Adrenergic Ligands and Receptors: Shared, Complementary Modules Explain Evolution of Functional Interactions and Suggest Novel Engineering Possibilities

Cross-talk between opioid and adrenergic receptors is well-characterized and involves second messenger systems, the formation of receptor heterodimers, and the presence of extracellular allosteric binding regions for the complementary ligand; however, the evolutionary origins of these interactions have not been investigated. We propose that opioid and adrenergic ligands and receptors co-evolved from a common set of modular precursors so that they share binding functions. We demonstrate the plausibility of this hypothesis through a review of experimental evidence for molecularly complementary modules and report unexpected homologies between the two receptor types. Briefly, opioids form homodimers also bind adrenergic compounds; opioids bind to conserved extracellular regions of adrenergic receptors while adrenergic compounds bind to conserved extracellular regions of opioid receptors; opioid-like modules appear in both sets of receptors within key ligand-binding regions. Transmembrane regions associated with homodimerization of each class of receptors are also highly conserved across receptor types and implicated in heterodimerization. This conservation of multiple functional modules suggests opioid–adrenergic ligand and receptor co-evolution and provides mechanisms for explaining the evolution of their crosstalk. These modules also suggest the structure of a primordial receptor, providing clues for engineering receptor functions.

Glutathione and Glutathione-Like Sequences of Opioid and Aminergic Receptors Bind Ascorbic Acid, Adrenergic and Opioid Drugs Mediating Antioxidant Function: Relevance for Anesthesia and Abuse

Opioids and their antagonists alter vitamin C metabolism. Morphine binds to glutathione (l-γ-glutamyl-l-cysteinyl-glycine), an intracellular ascorbic acid recycling molecule with a wide range of additional activities. The morphine metabolite morphinone reacts with glutathione to form a covalent adduct that is then excreted in urine. Morphine also binds to adrenergic and histaminergic receptors in their extracellular loop regions, enhancing aminergic agonist activity. The first and second extracellular loops of adrenergic and histaminergic receptors are, like glutathione, characterized by the presence of cysteines and/or methionines, and recycle ascorbic acid with similar efficiency. Conversely, adrenergic drugs bind to extracellular loops of opioid receptors, enhancing their activity. These observations suggest functional interactions among opioids and amines, their receptors, and glutathione. We therefore explored the relative binding affinities of ascorbic acid, dehydroascorbic acid, opioid and adrenergic compounds, as well as various control compounds, to glutathione and glutathione-like peptides derived from the extracellular loop regions of the human beta 2-adrenergic, dopamine D1, histamine H1, and mu opioid receptors, as well as controls. Some cysteine-containing peptides derived from these receptors do bind ascorbic acid and/or dehydroascorbic acid and the same peptides generally bind opioid compounds. Glutathione binds not only morphine but also naloxone, methadone, and methionine enkephalin. Some adrenergic drugs also bind to glutathione and glutathione-like receptor regions. These sets of interactions provide a novel basis for understanding some ways that adrenergic, opioid and antioxidant systems interact during anesthesia and drug abuse and may have utility for understanding drug interactions.

Switching properties of Li-benzene complexes in a uniform electric field: a case where a "small" change makes a big difference

The effect of a homogeneous static electric field on the Li-benzene complex in two configurations, one with a larger Li-C6H6 distance ("loose") and one with a shorter distance ("tight"), has been investigated. The electric field has the same orientation as the direction of the dipole moments of the complexes. When the direction of the field intensity vector was the same as that of the dipole moment vector, optimization of the complex's geometry in one configuration resulted in switching it to the other one. Reversing the direction of the field then transformed the other configuration back to the original one. This switching behavior was observed beginning with the loose configuration and with the tight configuration. The geometrical and electronic parameters of the complex after four steps of the reversible switching have been calculated for a selected field intensity of 0.005 atomic units (a.u.), that is 0.257 V Å(-1).

Neurobiological basis of motivational deficits in psychopathology

In recent years, there has been increasing emphasis on the importance of motivational symptoms in depression, schizophrenia and other disorders. The present review discusses the conceptual background related to the construct of motivation, and provides a framework that for research on both physiological and pathological aspects of motivation. Particular emphasis is placed on what is known about the neurobiological basis of activational aspects of motivation, including studies from animal models. The role of limbic/prefrontal/striatal circuitry in behavioral activation and effort-related functions is examined, and the utility of behavioral tasks of effort-based decision making as models of motivational symptoms is discussed. We also review the neurobiology of motivational symptoms in relation to psychopathology, and issues related to the language used to characterize motivational dysfunctions are considered. The literature suggests that research on the neurobiology of motivational dysfunction in psychopathology, at both clinical and preclinical levels, could inform the development of novel and more effective treatments for a range of CNS disorders.

Estradiol Binds to Insulin and Insulin Receptor Decreasing Insulin Binding in vitro

RATIONALE

Insulin (INS) resistance associated with hyperestrogenemias occurs in gestational diabetes mellitus, polycystic ovary syndrome, ovarian hyperstimulation syndrome, estrogen therapies, metabolic syndrome, and obesity. The mechanism by which INS and estrogen interact is unknown. We hypothesize that estrogen binds directly to INS and the insulin receptor (IR) producing INS resistance.

OBJECTIVES

To determine the binding constants of steroid hormones to INS, the IR, and INS-like peptides derived from the IR; and to investigate the effect of estrogens on the binding of INS to its receptor.

METHODS

Ultraviolet spectroscopy, capillary electrophoresis, and NMR demonstrated estrogen binding to INS and its receptor. Horse-radish peroxidase-linked INS was used in an ELISA-like procedure to measure the effect of estradiol on binding of INS to its receptor.

MEASUREMENTS

Binding constants for estrogens to INS and the IR were determined by concentration-dependent spectral shifts. The effect of estradiol on INS binding to its receptor was determined by shifts in the INS binding curve.

MAIN RESULTS

Estradiol bound to INS with a K d of 12 × 10(-9) M and to the IR with a K d of 24 × 10(-9) M, while other hormones had significantly less affinity. Twenty-two nanomolars of estradiol shifted the binding curve of INS to its receptor 0.8 log units to the right.

CONCLUSION

Estradiol concentrations in hyperestrogenemic syndromes may interfere with INS binding to its receptor producing significant INS resistance.

Human protein kinase inhibitor screening by capillary electrophoresis using transverse diffusion of laminar flow profiles for reactant mixing

A capillary electrophoresis (CE)-based enzyme assay method has been developed to screen protein kinase inhibitors. Four human kinases GSK3β, DYRK1A, CDK5/p25 and CDK1/cyclin B were chosen to test this novel method. These enzymes have been identified as very promising targets to develop treatments against cancer and neurodegenerative diseases. The efficiency of drugs against these relevant biological targets has never been carried out by CE. For this proposal, the capillary was used as a nanoreactor in which four reactants (the enzyme, its two substrates and its potential inhibitor) were successively injected, mixed by using transverse diffusion of laminar flow profiles and incubated. The adenosine 5'-diphosphate (ADP) formed during the enzymatic reaction was detected by UV and quantified. The efficiency of the developed CE method was validated by determining the IC50 values of a wide variety of inhibitors covering a large domain of affinity toward kinases and containing representative and chemically divergent skeletons. Excellent agreement was found between the results obtained by CE and those reported in the literature when using conventional radiometric enzyme assays. Moreover, CE was successfully used to determine the inhibitory effect of several potential inhibitors that was not yet assessed by conventional methods and is crucial for structure activity relation studies. This novel CE method is simple, rapid, very economic (few tens of nanoliters per IC50) and eco-friendly since no radioactivity was required. It could be extended to high-throughput screening of kinase inhibitors, which is of great interest for biomedical and pharmaceutical research fields.