Review

The chalcogen elements oxygen, sulfur, and selenium are essential constituents of side chain functions of natural amino acids. Conversely, no structural and biological function has been discovered so far for the heavier and more metallic tellurium element. In the methionine series, only the sulfur-containing methionine is a proteinogenic amino acid, while selenomethionine and telluromethionine are natural amino acids that are incorporated into proteins most probably because of the tolerance of the methionyl-tRNA synthetase; so far, methoxinine the oxygen analogue has not been discovered in natural compounds. Similarly, the chalcogen analogues of tryptophan and phenylalanine in which the benzene ring has been replaced by the largely isosteric thiophene, selenophene, and more recently, even tellurophene are fully synthetic mimics that are incorporated with more or less efficiency into proteins via the related tryptophanyl- and phenylalanyl-tRNA synthetases, respectively. In the serine/cysteine series, also selenocysteine is a proteinogenic amino acid that is inserted into proteins by a special translation mechanism, while the tellurocysteine is again most probably incorporated into proteins by the tolerance of the cysteinyl-tRNA synthetase. For research purposes, all of these natural and synthetic chalcogen amino acids have been extensively applied in peptide and protein research to exploit their different physicochemical properties for modulating structural and functional properties in synthetic peptides and rDNA expressed proteins as discussed in the following review

Reassessment of an Innovative Insulin Analogue Excludes Protracted Action yet Highlights Distinction between External and Internal Diselenide Bridges

Long-acting insulin analogues represent the most prescribed class of therapeutic proteins. An innovative design strategy was recently proposed: diselenide substitution of an external disulfide bridge. This approach exploited the distinctive physicochemical properties of selenocysteine (U). Relative to wild type (WT), Se-insulin[C7UA , C7UB ] was reported to be protected from proteolysis by insulin-degrading enzyme (IDE), predicting prolonged activity. Because of this strategy's novelty and potential clinical importance, we sought to validate these findings and test their therapeutic utility in an animal model of diabetes mellitus. Surprisingly, the analogue did not exhibit enhanced stability, and its susceptibility to cleavage by either IDE or a canonical serine protease (glutamyl endopeptidase Glu-C) was similar to WT. Moreover, the analogue's pharmacodynamic profile in rats was not prolonged relative to a rapid-acting clinical analogue (insulin lispro). Although [C7UA , C7UB ] does not confer protracted action, nonetheless its comparison to internal diselenide bridges promises to provide broad biophysical insight

Efficacy and safety of Apixaban in the treatment of cerebral venous sinus thrombosis: a multi-center study

BackgroundInformation regarding the safety and efficacy of specific direct oral anticoagulants (DOAC) in the treatment of cerebral sinus and venous thrombosis (CSVT) is scarce. Apixaban is one of the most frequently prescribed DOACs. Therefore, we aimed to compare the safety and efficacy of Apixaban with those of vitamin k antagonists (VKA) in patients with CSVT.MethodsProspective CSVT databases from seven academic medical centers were retrospectively analyzed. Patients treated with Apixaban were compared to those treated with VKA. Data on demographics, clinical presentations, risk factors, radiological and outcome parameters were studied.ResultsOverall, 403 patients were included in the analysis. Of them, 48 (12%) were treated with Apixaban, and 355 (88%) were treated with VKA. Rates of coagulopathies were significantly higher in the VKA-treated patients but no other differences between the groups were found in baseline characteristics and underlying etiology. No significant differences were found between groups in efficacy or safety parameters including the rates of recanalization, favorable outcomes, one-year mortality, seizures, intracranial hemorrhage or CSVT recurrences.ConclusionOur data suggests that Apixaban may be safe and effective for patients with CSVT. These results should be tested in prospective randomized clinical studies

One-pot ligation-oxidative deselenization at selenocysteine and selenocystine

The use of native chemical ligation at selenocysteine (Sec) with peptide thioesters and additive-free selenocystine ligation with peptides bearing phenyl selenoesters, in concert with one-pot oxidative deselenization chemistry, is described. These approaches provide a simple and rapid method for accessing native peptides with serine in place of Sec at the ligation junction. The efficiency of both variants of the one-pot ligation-oxidative deselenization chemistry is probed through the synthesis of a MUC5AC-derived glycopeptide

ETIICA study

Publisher Copyright: © European Stroke Organisation 2025.Introduction: Evidence regarding the benefit of endovascular therapy (EVT) in patients with acute ischemic stroke (AIS) due to isolated cervical internal carotid artery occlusion (c-ICA-O) is lacking. We assessed the outcomes and safety of EVT in patients with isolated c-ICA-O. Methods: Retrospective multicenter cohort study of patients with an AIS due to isolated c-ICA-O, within 24-h since last-seen-well. Comparisons were made between EVT and best medical therapy (BMT). The primary outcome was 3-months modified Rankin Scale (mRS) ordinal shift. Secondary outcomes included 3-month favorable outcome (mRS 0–2, or return to pre-stroke mRS), symptomatic intracranial hemorrhage (sICH) and any parenchymal hemorrhage. Outcomes were compared combining inverse probability of treatment weighting with regression models and propensity score matching (PSM) as sensitivity analysis. Results: We analyzed 998 patients (66.2% male, mean age 71.1 ± 13.2 years). 487 (48.8%) patients received EVT and 511 (51.2%) received BMT. Patients receiving EVT had a higher admission NIHSS [13 (7–18) vs 5 (2–13)] compared to BMT. There was no difference between EVT and BMT groups in 3-month mRS shift (adjusted common odds ratio [OR], 1.01 [95% CI 0.76–1.34]) and favorable outcome (adjusted OR [aOR] 1.16 [95% CI 0.84–1.60]). No patient (0%) in the BMT group had sICH versus 1.6% in the EVT group. Parenchymal hemorrhage was numerically higher in EVT patients (2.7% vs 0.6%; aOR 3.85 [95% CI 0.98–15.23]). PSM analysis revealed similar results. Discussion and conclusion: In patients with isolated c-ICA-O, EVT was associated with similar odds of disability and intracranial bleeding compared to BMT. Randomized-controlled clinical trials in patients with isolated c-ICA-O are warranted.publishersversioninpres

Oxidative Deselenization of Selenocysteine: Applications for Programmed Ligation at Serine

Despite the unique chemical properties of selenocysteine (Sec), ligation at Sec is an under‐utilized methodology for protein synthesis. We describe herein an unprecedented protocol for the conversion of Sec to serine (Ser) in a single, high‐yielding step. When coupled with ligation at Sec, this transformation provides a new approach to programmed ligations at Ser residues. This new reaction is compatible with a wide range of functionality, including the presence of unprotected amino acid side chains and appended glycans. The utility of the methodology is demonstrated in the rapid synthesis of complex glycopeptide fragments of the epithelial glycoproteins MUC5AC and MUC4 and through the total synthesis of the structured, cysteine (Cys)‐free protein eglin C

Copper-mediated selenazolidine deprotection enables one-pot chemical synthesis of challenging proteins

&lt;p&gt;While chemical protein synthesis (CPS) has granted access to challenging proteins, synthesis of longer proteins is often limited by low abundance or non-strategic placement of cysteine (Cys) residues, essential for native chemical ligations (NCL), as well as multiple purification and isolation steps. Selective deselenization and one-pot CPS serve as key technologies to circumvent these issues. Herein, we describe the one-pot total synthesis of human thiosulfate: glutathione sulfurtransferase (TSTD1), a 115-residue protein with a single Cys residue at its active site, and its seleno-analogue. WT-TSTD1 was synthesized in a C-to-N synthetic approach employing multiple NCL reactions, Cu(II)-mediated deprotection of selenazolidine (Sez), and chemoselective deselenization, all in one-pot. In addition, the protein’s seleno analogue (Se-TSTD1), in which the active site Cys is replaced with selenocysteine, was synthesized with a kinetically controlled ligation in a one-pot, N-to-C synthetic approach. TSTD1’s one-pot synthesis was made possible by the newly reported, rapid, and facile copper-mediated selenazolidine deprotection that can be accomplished in one minute. Finally, catalytic activity of the two proteins indicated that Se-TSTD1 possessed only four-fold lower activity than WT-TSTD1 as a thiosulfate: glutathione sulfurtransferase, suggesting that selenoproteins can have physiologically comparable sulfutransferase activity as their cysteine counterparts. &lt;/p&gt;</jats:p

Copper-mediated selenazolidine deprotection enables one-pot chemical synthesis of challenging proteins

While chemical protein synthesis (CPS) has granted access to challenging proteins, synthesis of longer proteins is often limited by low abundance or non-strategic placement of cysteine (Cys) residues, essential for native chemical ligations (NCL), as well as multiple purification and isolation steps. Selective deselenization and one-pot CPS serve as key technologies to circumvent these issues. Herein, we describe the one-pot total synthesis of human thiosulfate: glutathione sulfurtransferase (TSTD1), a 115-residue protein with a single Cys residue at its active site, and its seleno-analogue. WT-TSTD1 was synthesized in a C-to-N synthetic approach employing multiple NCL reactions, Cu(II)-mediated deprotection of selenazolidine (Sez), and chemoselective deselenization, all in one-pot. In addition, the protein’s seleno analogue (Se-TSTD1), in which the active site Cys is replaced with selenocysteine, was synthesized with a kinetically controlled ligation in a one-pot, N-to-C synthetic approach. TSTD1’s one-pot synthesis was made possible by the newly reported, rapid, and facile copper-mediated selenazolidine deprotection that can be accomplished in one minute. Finally, catalytic activity of the two proteins indicated that Se-TSTD1 possessed only four-fold lower activity than WT-TSTD1 as a thiosulfate: glutathione sulfurtransferase, suggesting that selenoproteins can have physiologically comparable sulfutransferase activity as their cysteine counterparts. </p