The 7-azanorbornane nucleus of epibatidine: 7-azabicyclo[2.2.1]heptan-7-ium chloride

7-Azabicyclo[2.2.1]heptane (7-azanorbornane) is a bridged heterocyclic nucleus found in epibatidine, the alkaloid isolated from the skin of the tropical poison frog Epipedobates tricolor. Since epibatidine is known as one of the most potent acetylcholine nicotinic receptor agonists, a plethora of literature has been devoted to this alkaloid. However, there are no structural data on the unsubstituted 7-azanorbornane, the parent bicyclic ring of epibatidine and its derivatives. We herein present the structural characterization of the 7-azabicyclo[2.2.1]heptane parent ring as its hydrochloride salt, namely 7-azabicyclo[2.2.1]heptan-7-ium chloride, C6H12N+·Cl−. The compete cation is generated by a crystallographic mirror plane with the N atom lying on the mirror, as does the chloride anion. In the crystal, the cations are linked to the anions by N—H...Cl hydrogen bonds, which generate [001] chains

Crystal structure of (1R,5S)-endo-(8-methyl-8-azoniabicyclo[3.2.1]oct-3-yl)ammonium aquatrichloridonitratocopper(II)

The structure of a salt of diprotonated endo-3-aminotropane crystallized with a copper(II) anionic cluster is reported, viz. (C8H18N2)[CuCl3(NO3)(H2O)]. Neither ion in the salt has been structurally characterized previously. In the crystal, the ions pack together to form a three-dimensional structure held together by a network of intermolecular N—H...O, O—H...Cl and N—H...Cl hydrogen-bonding interactions. Selective crystallization of the title compound can be considered as a simple method for the separation of the exo and endo isomers of 3-aminotropane

Cytokinin biosynthesis genes expressed during nodule organogenesis are directly regulated by the KNOX3 protein in Medicago truncatula.

Cytokinin is an important regulator of symbiotic nodule development. Recently, KNOTTED1-LIKE HOMEOBOX 3 transcription factor (TF) was shown to regulate symbiotic nodule development possibly via the activation of cytokinin biosynthesis genes. However, the direct interaction between the KNOX3 TF and its target genes has not been investigated up to date. Here, using EMSA analysis and SPR-based assay, we found that MtKNOX3 homeodomain directly binds to the regulatory sequences of the MtLOG1, MtLOG2, and MtIPT3 genes involved in nodulation in Medicago truncatula. Moreover, we showed that MtLOG2 and MtIPT3 expression patterns partially overlap with MtKNOX3 expression in developing nodules as it was shown by promoter:GUS analysis. Our data suggest that MtKNOX3 TF may directly activate the MtLOG1, MtLOG2, and MtIPT3 genes during nodulation thereby increasing cytokinin biosynthesis in developing nodules

4,5-Bis(arylethynyl)-1,2,3-triazoles - A New Class of Fluorescent Labels: Synthesis and Applications

Cu-catalyzed 1,3-dipolar cycloaddition of ethyl 2-azidoacetate to iodobuta-1,3-diynes and subsequent Sonogashira cross-coupling were used to synthesize a large series of new triazole-based push–pull chromophores: 4,5-bis(arylethynyl)-1H-1,2,3-triazoles. The study of their optical properties revealed that all molecules have fluorescence properties, the Stokes shift values of which exceed 150 nm. The fluorescent properties of triazoles are easily adjustable depending on the nature of the substituents attached to aryl rings of the arylethynyl moieties at the C4 and C5 atoms of the triazole core. The possibility of 4,5-bis(arylethynyl)-1,2,3-triazoles’ application for labeling was demonstrated using proteins and the HEK293 cell line. The results of an MTT test on two distinct cell lines, HEK293 and HeLa, revealed the low cytotoxicity of 4,5-bis(arylethynyl)triazoles, which makes them promising fluorescent tags for labeling and tracking biomolecules

The Structure of T-DNA Insertions in Transgenic Tobacco Plants Producing Bovine Interferon-Gamma

Many of the most modern drugs are of a protein nature and are synthesized by transgenic producer organisms. Bacteria, yeast, or animal cell cultures are commonly used, but plants have a number of advantages—minimal biomass unit cost, animal safety (plants are not attacked by mammalian pathogens), the agricultural scale of production, and the ability to produce complex proteins. A disadvantage of plants may be an unstable level of transgene expression, which depends on the transgene structure and its insertion site. We analyzed the structure of T-DNA inserts in transgenic tobacco plants (Nicotiana tabacum L.) belonging to two lines obtained using the same genetic construct but demonstrating different biological activities of the recombinant protein (bovine interferon-gamma). We found that, in one case, T-DNA was integrated into genomic DNA in the region of centromeric repeats, and in the other, into a transcriptionally active region of the genome. It was also found that in one case, the insert has a clustered structure and consists of three copies. Thus, the structure of T-DNA inserts in both lines is not optimal (the optimal structure includes a single copy of the insert located in the active region of the genome). It is desirable to carry out such studies at the early stages of transgenic plants selection

The Structure of T-DNA Insertions in Transgenic Tobacco Plants Producing Bovine Interferon-Gamma

Many of the most modern drugs are of a protein nature and are synthesized by transgenic producer organisms. Bacteria, yeast, or animal cell cultures are commonly used, but plants have a number of advantages—minimal biomass unit cost, animal safety (plants are not attacked by mammalian pathogens), the agricultural scale of production, and the ability to produce complex proteins. A disadvantage of plants may be an unstable level of transgene expression, which depends on the transgene structure and its insertion site. We analyzed the structure of T-DNA inserts in transgenic tobacco plants (Nicotiana tabacum L.) belonging to two lines obtained using the same genetic construct but demonstrating different biological activities of the recombinant protein (bovine interferon-gamma). We found that, in one case, T-DNA was integrated into genomic DNA in the region of centromeric repeats, and in the other, into a transcriptionally active region of the genome. It was also found that in one case, the insert has a clustered structure and consists of three copies. Thus, the structure of T-DNA inserts in both lines is not optimal (the optimal structure includes a single copy of the insert located in the active region of the genome). It is desirable to carry out such studies at the early stages of transgenic plants selection

4-Azidocinnoline—Cinnoline-4-amine Pair as a New Fluorogenic and Fluorochromic Environment-Sensitive Probe

A new type of fluorogenic and fluorochromic probe based on the reduction of weakly fluorescent 4-azido-6-(4-cyanophenyl)cinnoline to the corresponding fluorescent cinnoline-4-amine was developed. We found that the fluorescence of 6-(4-cyanophenyl)cinnoline-4-amine is strongly affected by the nature of the solvent. The fluorogenic effect for the amine was detected in polar solvents with the strongest fluorescence increase in water. The environment-sensitive fluorogenic properties of cinnoline-4-amine in water were explained as a combination of two types of fluorescence mechanisms: aggregation-induced emission (AIE) and excited state intermolecular proton transfer (ESPT). The suitability of an azide–amine pair as a fluorogenic probe was tested using a HepG2 hepatic cancer cell line with detection by fluorescent microscopy, flow cytometry, and HPLC analysis of cells lysates. The results obtained confirm the possibility of the transformation of the azide to amine in cells and the potential applicability of the discovered fluorogenic and fluorochromic probe for different analytical and biological applications in aqueous medium