Mechanism investigation of pseudouridine synthases TruB and RluA with RNA containing 5-fluorouridine and 4-thiouridine.

Pseudouridine synthases (Ψ synthases) are the enzymes that catalyze the isomerization of uridine (U) to pseudouridine (Ψ), which is the most prevalent post-transcriptional modification of RNA. The Ψ synthases fall into six different families that share no significant global sequence similarity; however, they all involve a conserved aspartic acid residue which is absolutely essential for activity. Tyrosine is a conserved residue in the active site in five of the six families of Ψ synthases (phenylalanine in the TruD family) and was hypothesized as the general base for the isomerization reaction. To confirm the function of Tyr-96, Y96F RluA was assayed with both ASL and [F5U]ASL. U is converted to Ψ and F5U to F5U products. These results argue against the role of Tyr serving as general base. However, the slow rates of reactions and higher concentration of Y96F RluA needed for any reaction indicates that Tyr-96 does facilitates at least one step of the reaction. The major product of F5U from the action of Ψ synthases is a ribo isomer whereas the minor product is arabino, and its generation requires epimerization at C2′. The deprotonation at C2′ can be achieved by the conserved Asp or O2. To test if O2 is the general base, the isomerized U was replaced by 4-thiouridine (s4U). As an essential first step, RNA containing s4U needs to be verified as a good substrate for Ψ synthases, so RluA and TruB were incubated with [s4U]RNA. Intact [s4U]RNA shifted to later and shorter retention times after incubation with RluA and TruB, respectively. Traces of the digestion products of [s4U]RNA after incubation with the two enzymes also showed the new peaks that absorbed more strongly at 330 nm than 260 nm. These results indicate that [s4U]RNA can be handled as a substrate

Micellar nanocatalysis for efficient reactions.

Water is considered a green, sustainable, and inexpensive solvent for organic synthesis. However, performing organic reactions in water is especially challenging due to the inherent insolubility of substrates and catalysts. Inspired from Nature, where chemistry happens in water, micellar catalysis has recently gained much attention, especially for applications in pharmaceutical industry. Aqueous micelles are generally formed by amphiphile`s self-aggregation, a particular class of molecules possessing both hydrophobic and hydrophilic components. The aqueous micelle contains a hydrophobic cavity, which allows the lipophilic substrates and catalyst to go inside micelles, allowing their much higher localized concentration that enhances the reaction rates and improves the purity profile. In this direction, our group has developed a proline-based amphiphile PS-750-M that mimics dipolar-aprotic solvents, such as DMF, DMAc, and NMP. Under the environment of micelles of PS-750-M, various valued organic transformations were effectively achieved in aqueous conditions, especially the transformations involving unstable reaction intermediates. Carbene is an important reaction intermediate in many organic transformations. However, it is highly water-sensitive, and reactions involving this intermediate usually require anhydrous and toxic organic solvents. With our approach, the nanomicelles derived from PS-750-M shield the in-situ generated carbene further preventing its dimerization and enable the desired coupling reactions. The sustainability of the reaction system is demonstrated by the recyclability of both the nanoparticle catalyst and the micellar reaction medium at variable reaction scales. Likewise, to explore the reactivity of persistent radicals under micellar conditions, a heterogeneous Cu-based catalyst has been developed and employed for the oxidation of benzylic alcohols to aldehydes in water under mild conditions. A broad substrate scope, excellent selectivity, and no over-oxidation reveal the catalyst robustness. In addition, the catalyst is entirely recyclable and reuse without significant loss in activity after three cycles. Additionally, trimetallic nanoparticles are developed to enable selective Suzuki-Miyaura (SM) couplings of aryl boronate esters and aryl halides containing terminal olefins. Generally, these substrates participate in the Heck coupling reaction to generate unwanted polymeric and other byproducts. However, no byproducts were observed under our micellar conditions. This technology provides a mild and valuable access to diverse functionalized styrene-type molecules. Finally, although hydroboration of terminal alkynes in aqueous conditions are well documented, the hydroboration of unsymmetrical internal alkynes is still underexplored due to poor selectivity. Using simple Cu(OAc)2 with ppm level of Pd(OAc)2 ligated with PCy3, a mild and highly regioselective of -hydroboration of unsymmetric internal alkynes has been developed using the aqueous micellar conditions

Analytical study of the sth-order perturbative corrections to the solution to a one-dimensional harmonic oscillator perturbed by a spatially power-law potential Vper(x) = λxα

In this work, we present a rigorous mathematical scheme for the derivation of the sth-order perturbative corrections to the solution to a one-dimensional harmonic oscillator perturbed by the potential V-per(x) = lambda x(alpha), where alpha is a positive integer, using the non-degenerate time-independent perturbation theory. To do so, we derive a generalized formula for the integral I = integral(+infinity)(-infinity)x(alpha)exp(-x(2))H-n(x)H-m(x)d(x), where H-n(x) denotes the Hermite polynomial of degree n, using the generating function of orthogonal polynomials. Finally, the analytical results with alpha = 3 and alpha = 4 are discussed in detail and compared with the numerical calculations obtained by the Lagrange-mesh method

Improvement of precision of numerical calculations using “multiple precision computation” package

In this work, the program so-called “Multiple Precision Computation” (MPC) proposed by Smith in 2003 is introduced and embedded into conventional codes for considerably improving the precision of numerical calculations. The procedure is evaluated for improvement and validated by using the comparison between calculations incorporating MPC and those using regular double-precision declarations and results obtained with well-known software Mathematica, respectively. Several representatively fundamental problems are taken into account for illustration

The risk of fever following one dose of trivalent inactivated influenza vaccine in children aged ≥6 months to <36 months: A comparison of published and unpublished studies

There are limited summary data published on the risk of fever and febrile seizures in children following influenza vaccination. We performed a review of the risk of fever and febrile seizures following receipt of trivalent inactivated influenza vaccine (

A meta-analysis of prognostic roles of molecular markers in papillary thyroid carcinoma

The prognostic role of molecular markers in papillary thyroid carcinoma (PTC) is a matter of ongoing debate. The aim of our study is to investigate the impact of RAS, BRAF, TERT promoter mutations and RET/PTC rearrangements on the prognosis of PTC patients. We performed a search in four electronic databases: PubMed, Scopus, Web of Science and Virtual Health Library (VHL). Data of hazard ratio (HR) and its 95% confidence interval (CI) for disease-specific survival (DSS) and disease-free survival (DFS) were directly obtained from original papers or indirectly estimated from Kaplan–Meier curve (KMC). Pooled HRs were calculated using random-effect model weighted by inverse variance method. Publication bias was assessed by using Egger’s regression test and visual inspection of funnel plots. From 2630 studies, we finally included 35 studies with 17,732 patients for meta-analyses. TERT promoter mutation was significantly associated with unfavorable DSS (HR = 7.64; 95% CI = 4.00–14.61) and DFS (HR = 2.98; 95% CI = 2.27–3.92). BRAF mutations significantly increased the risk for recurrence (HR = 1.63; 95% CI = 1.27–2.10) but not for cancer mortality (HR = 1.41; 95% CI = 0.90–2.23). In subgroup analyses, BRAF mutation only showed its prognostic value in short-/medium-term follow-up. Data regarding RAS mutations and RET/PTC fusions were insufficient for meta-analyses. TERT promoter mutation can be used as an independent and reliable marker for risk stratification and predicting patient’s outcomes. The use of BRAF mutation to assess patient prognosis should be carefully considered