Enantioselektive Synthese von (1S,4R)-4-Hydroxycyclopent-2-enyl-acetat durch enzym-katalysierte Veresterung von cis-Cyclopent-2-en-1,4-diol mit Acetanhydrid. Gaschromatographische Untersuchungen zum Reaktionsmechanismus

(1S,4R)-4-Hydroxycyclopent-2-enyl-acetate (1), an attractive starting material for the synthesis of prostaglandins, was readily prepared by an enzyme-catalyzed interesterification procedure using acetic anhydride as acylation agent. As the chemical yield of the chiral monoacylation product is rather low (45%), we investigated the acylation mechanism of this reaction to optimize the product output. Kinetic measurements were carried out by means of gas chromatography on a chiral stationary phase, synthesized by methylation of β-cyclodextrin

Middle Miocene Climate and Stable Oxygen Isotopes in Europe Based on Numerical Modeling

The Middle Miocene (15.99–11.65 Ma) of Europe witnessed major climatic, environmental, and vegetational change, yet we are lacking detailed reconstructions of Middle Miocene temperature and precipitation patterns over Europe. Here, we use a high-resolution (∼0.75°) isotope-enabled general circulation model (ECHAM5-wiso) with time-specific boundary conditions to investigate changes in temperature, precipitation, and δ18O in precipitation (δ18Op). Experiments were designed with variable elevation configurations of the European Alps and different atmospheric CO2 levels to examine the influence of Alpine elevation and global climate forcing on regional climate and δ18Op patterns. Modeling results are in agreement with available paleobotanical temperature data and with low-resolution Middle Miocene experiments of the Miocene Model Intercomparison Project (MioMIP1). However, simulated precipitation rates are 300–500 mm/yr lower in the Middle Miocene than for pre-industrial times for central Europe. This result is consistent with precipitation estimates from herpetological fossil assemblages, but contradicts precipitation estimates from paleobotanical data. We attribute the Middle Miocene precipitation change in Europe to shifts in large-scale pressure patterns in the North Atlantic and over Europe and associated changes in wind direction and humidity. We suggest that global climate forcing contributed to a maximum δ18Op change of ∼2‰ over high elevation (Alps) and ∼1‰ over low elevation regions. In contrast, we observe a maximum modeled δ18Op decrease of 8‰ across the Alpine orogen due to Alpine topography. However, the elevation-δ18Op lapse rate shallows in the Middle Miocene, leading to a possible underestimation of paleotopography when using present-day δ18Op—elevation relationships data for stable isotope paleoaltimetry studies

A Presynaptic Role for the Cytomatrix Protein GIT in Synaptic Vesicle Recycling

Neurotransmission involves the exo-endocytic cycling of synaptic vesicles (SVs) within nerve terminals. Exocytosis is facilitated by a cytomatrix assembled at the active zone (AZ). The precise spatial and functional relationship between exocytic fusion of SVs at AZ membranes and endocytic SV retrieval is unknown. Here, we identify the scaffold G protein coupled receptor kinase 2 interacting (GIT) protein as a component of the AZ- associated cytomatrix and as a regulator of SV endocytosis. GIT1 and its D. melanogaster ortholog, dGIT, are shown to directly associate with the endocytic adaptor stonin 2/stoned B. In Drosophila dgit mutants, stoned B and synaptotagmin levels are reduced and stoned B is partially mislocalized. Moreover, dgit mutants show morphological and functional defects in SV recycling. These data establish a presynaptic role for GIT in SV recycling and suggest a connection between the AZ cytomatrix and the endocytic machinery

S-nitrosation and neuronal plasticity

Nitric oxide (NO) has long been recognized as a multifaceted participant in brain physiology. Despite the knowledge that was gathered over many years regarding the contribution of NO to neuronal plasticity, for example the ability of the brain to change in response to new stimuli, only in recent years have we begun to understand how NO acts on the molecular and cellular level to orchestrate such important phenomena as synaptic plasticity (modification of the strength of existing synapses) or the formation of new synapses (synaptogenesis) and new neurons (neurogenesis). Post-translational modification of proteins by NO derivatives or reactive nitrogen species is a non-classical mechanism for signalling by NO. S-nitrosation is a reversible post-translational modification of thiol groups (mainly on cysteines) that may result in a change of function of the modified protein. S-nitrosation of key target proteins has emerged as a main regulatory mechanism by which NO can influence several levels of brain plasticity, which are reviewed in this work. Understanding how S-nitrosation contributes to neural plasticity can help us to better understand the physiology of these processes, and to better address pathological changes in plasticity that are involved in the pathophysiology of several neurological diseases. Linked ArticlesThis article is part of a themed section on Pharmacology of the Gasotransmitters. To view the other articles in this section visitFEDER funds via Programa Operacional Factores de Competitividade (COMPETE); COST action [BM1005]; Foundation for Science and Technology (FCT, Portugal) [PTDC/SAU-OSD/0473/2012, PEst-C/SAU/LA0001/2013-2014, PEst-OE/EQB/LA0023/2013-2014]; Spanish-Portuguese Integrated Action grant [PRI-AIBPT-2011-1015/E-10/12]; FCT [SFRH/BD/77903/2011]; I3SNS programme (ISCIII, Spanish Government

The evolving small-molecule fluorescent-conjugate toolbox for Class A GPCRs

The past decade has witnessed fluorescently tagged drug molecules gaining significant attraction in their use as pharmacological tools with which to visualize and interrogate receptor targets at the single-cell level. Additionally, one can generate detailed pharmacological information, such as affinity measurements, down to almost single-molecule detection limits. The now accepted utilization of fluorescence-based readouts in high-throughput/high-content screening provides further evidence that fluorescent molecules offer a safer and more adaptable substitute to radioligands in molecular pharmacology and drug discovery. One such drug-target family that has received considerable attention are the GPCRs; this review therefore summarizes the most recent developments in the area of fluorescent ligand design for this important drug target. We assess recently reported fluorescent conjugates by adopting a receptor-family-based approach, highlighting some of the strengths and weaknesses of the individual molecules and their subsequent use. This review adds further strength to the arguments that fluorescent ligand design and synthesis requires careful planning and execution; providing examples illustrating that selection of the correct fluorescent dye, linker length/composition and geographic attachment point to the drug scaffold can all influence the ultimate selectivity and potency of the final conjugate when compared with its unlabelled precursor. When optimized appropriately, the resultant fluorescent conjugates have been successfully employed in an array of assay formats, including flow cytometry, fluorescence microscopy, FRET and scanning confocal microscopy. It is clear that fluorescently labelled GPCR ligands remain a developing and dynamic research arena