A major challenge in the field of RNA chemistry is the identification of selective and quantitative conversion reactions on RNA that can be used for tagging and any other RNA tool development. Here, we introduce metal-free diazotransfer on native RNA containing an aliphatic primary amino group using the diazotizing reagent fluorosulfuryl azide (FSO 2 N 3). The reaction provides the corresponding azidemodified RNA in nearly quantitatively yields without affecting the nucleobase amino groups. The obtained azido-RNA can then be further processed utilizing well-established bioorthogonal reactions, such as azide-alkyne cycloadditions (Click) or Staudinger ligations. We exemplify the robustness of this approach for the synthesis of peptidyl-tRNA mimics and for the pull-down of 3-(3-amino-3-carboxypropyl)uridine (acp 3 U)-and lysidine (k 2 C)-containing tRNAs of an Escherichia coli tRNA pool isolated from cellular extracts. Our approach therefore adds a new dimension to the targeted chemical manipulation of diverse RNA species.

During pregnancy, substantial alterations in cerebral plasticity, vascular remodeling and neuronal growth occur in the maternal brain. We investigated whether concentrations of selected neurodiagnostic biomarkers in the cerebrospinal fluid of women with preeclampsia/HELLP syndrome differ from those in healthy controls using enzyme-linked immunosorbent assay technique. We found that tau protein concentrations (p = 0.016) and phospho-tau/tau ratio (p < 0.001) in cerebrospinal fluid were significantly lower in 39 preeclamptic women compared to 44 healthy controls during third trimester of pregnancy. Beta-amyloid(1-40)/(1-42) ratio was significantly higher in HELLP syndrome than in severe preeclampsia (8.49 + 2.73 vs. 4.71 + 1.65; p = 0.007). We conclude that betaamyloid(1-40)/(1-42) ratio in cerebrospinal fluid can discriminate severe preeclampsia and HELLP syndrome. High beta-amyloid peptide and low tau protein concentrations are associated with impaired development of the materno-feto-placental unit and correlate with placental dysfunction. During pregnancy, the invasion of trophoblast cells into maternal tissue of the uterus and the conversion of spiral arteries into wide sinusoids with low resistance and high flow are paramount for normal placental development 1. In preeclampsia (PE) placental development is impaired by defective deep placentation, platelet and thrombin activation, intravascular inflammation, endothelial dysfunction and imbalanced angiogenesis 2. Altered expression of proteins comes along with excess of antiangiogenic substances such as soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) and decreased levels of proangiogenic substances like placental growth factor (PlGF) and vascular endothelial growth factor A (VEGF-A) 3. Ciampa et al. observed in 13 patients with PE altered concentrations of proteins related to signaling pathways important for vascular remodeling, inflammation, and neuronal growth 4. Recent studies have shown that PE shares pathophysiologic features with recognized misfolding disorders and aggregation of proteins 4-8. There are several dysregulated proteins in PE but it is not clear whether aggregated proteins induce defective trophoblast invasion 4. D'Souza et al. reported that neurotrophic factors influence the development of the materno-feto-placental unit during pregnancy 9. Altered blood-brain barrier and impaired cerebral autoregulation may affect erebral blood flow in the maternal brain 10. Aggregated beta-amyloid peptides were observed in PE as well as in Alzheimer's disease 7. The presence of beta-amyloid aggregates in placentas of women with PE and intrauterine growth restriction (IUGR) further supports the notion that this condition goes with protein conformational disorders 6,11. Moreover, it was observed that short peptides occupying the self-recognition sites of beta-amyloid inhibit beta-amyloid aggregation 8. The aim of this study was to determine whether CSF concentrations of beta-amyloid peptides and tau protein differ between women with PE...

Hydrolysis-resistant RNA-peptide conjugates that mimic peptidyl-tRNAs are frequently needed for structural and functional studies of protein synthesis in the ribosome. Such conjugates are accessible by chemical solid-phase synthesis, allowing for the utmost flexibility of both the peptide and the RNA sequence. Commonly used protection group strategies, however, have severe limitations with respect to generating the characteristic N α -formylmethionyl terminus because the formyl group of the conjugate synthesized at the solid support is easily cleaved during the final basic deprotection/release step. In this study, we demonstrate a simple solution to the problem by coupling appropriately activated N α -formyl methionine to the fully deprotected conjugate. The structural integrity of the obtained N α -formylmethionyl conjugate�and hence the chemoselectivity of the reaction�were verified by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry sequence analysis. Additionally, we confirmed the applicability of our procedure for structural studies by obtaining two structures of the ribosome in complex with either fMAI-nh-ACCA or fMFI-nh-ACCA in the P site and ACC-PMN in the A site of the bacterial ribosome at 2.65 and 2.60 Å resolution, respectively. In summary, our approach for hydrolysis-resistant N α -formylated RNA-peptide conjugates is synthetically straightforward and opens up new avenues to explore ribosomal translation with high-precision substrate mimics.

To evaluate changes in concentrations of selected biomarkers, neurotrophic factors, and growth factors in the cerebrospinal fluid during pregnancy. A prospective observational study was conducted in 32 pregnant women undergoing gynecological and obstetrical surgery under spinal anesthesia in a university hospital. Beta-amyloid(1–42) and beta-amyloid(1–40) peptides, brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, and vascular endothelial growth factor were analyzed in cerebrospinal fluid using an enzyme-linked immunosorbent assay. Eight women in second trimester pregnancy who underwent spinal anesthesia for gynecological or obstetrical surgery were compared with 24 matched women in third trimester pregnancies. CSF concentrations of beta-amyloid(1–42) were significantly higher in third trimester pregnancies (p = 0.025). During third trimester, the beta-amyloid ratio correlated with the vascular endothelial growth factor (rs = 0.657; p = 0.008). Higher concentrations of beta-amyloid(1–42) in cerebrospinal fluid of third trimester pregnancies and correlations between the beta-amyloid ratio and the vascular endothelial growth factor support the hypothesis that beta-amyloid peptides are involved in complex adaptive brain alterations during pregnancy.