azides Dotaz Zobrazit nápovědu
Copper-free click reactions between a dibenzoazocine derivative and azides derived from 5-methyluridine were investigated. The non-catalyzed reaction yielded both regioisomers in an approximately equivalent ratio. The NMR spectra of each regioisomer revealed conformational isomery. The ratio of isomers was dependent on the type of regioisomer and the type of solvent. The synthesis of various analogs, a detailed NMR study and computational modeling provided evidence that the isomery was dependent on the interaction of the azocine and pyrimidine parts.
Androstane brassinosteroid analogues with alpha-azido acid ester groups in position 17beta were synthesized from 2alpha,3alpha,17beta-trihydroxy-5alpha-androstan-6-one after the protection of the 2alpha,3alpha-diols upon treatment with the corresponding alpha-azido acid and the subsequent deprotection of the diol grouping. Six new castasterone analogues were prepared. The biological activities were evaluated in two bioassays: a rice lamina inclination test and bean second internode bioassays. The activities of the new analogues differ in these two bioassays.
- MeSH
- androstany chemická syntéza chemie MeSH
- azidy chemie MeSH
- estery MeSH
- hydroxidy chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The increasing popularity of peptides as promising molecular scaffolds for biomedical applications and as valuable biochemical probes makes new methods allowing for their modification highly desirable. We describe herein an optimized protocol based on a sequence of CuAAC click reactions and selective deprotection steps, which leads to an efficient multi-functionalization of synthetic peptides. The methodology has been successfully applied to the construction of defined heteroglycopeptides and fluorophore-quencher-containing probes for proteases. The developed chemistry thus represents an important addition to the available toolbox of methods enabling efficient postsynthetic modification of peptides. The commercial availability of numerous azide probes further greatly extends the application potential of the described methodology.
The synthesis and chromatographic evaluation of a series of new Cinchona derived chiral weak anion exchangers is presented. Huisgen Cu(I) mediated alkyne-azide cycloaddition, so-called click chemistry, was used as an immobilization strategy. In this way it was possible to immobilize about 90% of offered selector via 1,2,3-triazole linker, which displays a more efficient way of binding the selector to modified silica compared to common radical mediated thiol-ene addition. Problems associated with potential radical scavenging properties of chiral selectors thereby could be circumvented. The evaluation of the synthesized chiral stationary phases regarding chromatographic behavior was carried out using polar organic mode mobile phase composition and a set of representative chiral organic acids. Different loading densities revealed an optimum selector density of about 310μmol/g chiral stationary phase with respect to resolution and selectivity. A decrease of performance was observed for higher loading, indicating mutual spatial influence of selector units leading to sterical hindrance. In addition, we observed that the effect of free azide groups on retention is negligible and the overall chromatographic behavior is comparable to other Cinchona derived chiral stationary phases.
- MeSH
- alkyny chemie MeSH
- aminokyseliny chemie MeSH
- azidy chemie MeSH
- chinidin analogy a deriváty chemická syntéza chemie MeSH
- chinin analogy a deriváty chemická syntéza chemie MeSH
- chromatografie MeSH
- cykloadiční reakce MeSH
- iontová výměna MeSH
- karbamáty chemická syntéza chemie MeSH
- oxid křemičitý MeSH
- stereoizomerie MeSH
- syntetická chemie okamžité shody MeSH
- Publikační typ
- časopisecké články MeSH
Alkylation of per-6-azido-β-cyclodextrin by a suitable electrophilic reagent (cinnamyl bromide or propargyl bromide) gave a mixture of 3(I)-O and 2(I)-O regioisomers. After peracetylation and chromatographic separation on silica gel, pure isomers were isolated. Oxidative cleavage of cinnamyl double bond afforded the corresponding formylmethyl and carboxymethyl derivatives. The prepared scaffold molecules are equipped with two types of reactive groups which have a potential to serve as points of attachment for various compounds.
Paracoccus denitrificans cells undergo changes in protein composition upon exposure to azide, a known activator of the fumarate-nitrate reduction (FNR)-type transcription factor NarR. One of the most prominent protein species inducible by azide is a Fe/Mn-family superoxide dismutase (SOD). Azide induces SOD at protein, mRNA transcript, and enzyme activity levels in the aerobically growing cells. Since SOD expression remains unaffected in the fnrP-, nnr-, and narR-mutant strains, we postulate a mechanism independent of the known FNR-type regulators but involving a redox signal arising from the respiratory chain.
- MeSH
- azidy metabolismus MeSH
- bakteriální proteiny genetika metabolismus MeSH
- molekulární sekvence - údaje MeSH
- Paracoccus denitrificans enzymologie genetika MeSH
- regulace genové exprese enzymů MeSH
- regulace genové exprese u bakterií MeSH
- regulační geny MeSH
- sekvence aminokyselin MeSH
- superoxiddismutasa genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
