Internal Activation of Peptidyl Prolyl Thioesters in Native Chemical Ligation

Prolyl thioesters have shown significantly lower reactivities in native chemical ligation (NCL) in comparison to that of the alanyl thioester. This report describes a mild and efficient internal activation protocol of peptidyl prolyl thioesters in NCL without using any thiol-based additives, where the introduction of a 4-mercaptan substituent on the C-terminal proline significantly improves the reactivity of prolyl thioesters via the formation of a bicyclic thiolactone intermediate. The kinetic data indicate that the reaction rate is comparable to that of the reported data of alanyl thioesters, and the mechanistic studies suggest that the ligation of two peptide segments proceeds through an NCL-like pathway instead of a direct aminolysis, which ensures the chemoselectivity and compatibility of various amino acid side chains. This 4-mercaptoprolyl thioester-based protocol also allows an efficient one-pot ligation–desulfurization procedure. The utility of this method has been further demonstrated in the synthesis of a proline-rich region of Wilms tumor protein 1

Retrospective analysis of medical malpractice claims in tertiary hospitals of China: the view from patient safety

Objectives The study analysed medical malpractice claims to assess patient safety in hospitals. The information derived from malpractice claims reflects potential risks and could help lead to reducing medical errors and improving patient safety.Design, setting We analysed 4380 medical malpractice claims from 351 grade-A tertiary hospitals in China for 2008–2017. We examined the characteristics of medical errors and patient safety, including the types of medical errors, proportionate liabilities and payments for medical malpractice in different clinical specialties.Main outcome measures We assessed claim characteristics, payment amounts and liability.Results Our data analysis demonstrated that 72.5% of the claims involved medical errors, with average payments of US$31 430. The hospital’s errors in medical malpractice resulted in 41.4$41 733) and the lowest in stomatology (US$8822).Conclusions A previous study found that grade-A tertiary hospitals in China have similar medical error rates to general Chinese hospitals. 36Different specialties had different risk characteristics regarding medical errors, payments and proportionate liabilities. Orthopaedics had the highest number of malpractices claims and higher proportionate liability but lower death rates

PDTAC: Targeted photodegradation of GPX4 triggers Ferroptosis and potent antitumor immunity

Targeted degradation of proteins, especially those regarded as ‘undruggable’, attracts wide attention to develop novel potential therapeutic strategy. GPX4, a key enzyme regulating ferroptosis, is such a target whose inhibition is currently limited to molecules acting through covalently binding. Here, we have developed a targeted photolysis approach to achieve the efficiently degradation of GPX4. The Photo-Degradation TArgeting Chimeras (PDTACs) were synthesized by conjugating a clinically approved photosensitizer Verteporfin to GPX4-targeting peptides. Although the ligands themselves exhibit neither inhibitory nor degrading activity towards GPX4, these chimeras degraded selectively the target protein in living cells upon red-light irradiation. In contrast to the application of Verteporfin alone, the targeted photolysis of GPX4 resulted in dominant ferroptotic cell death in malignant cancer cells of different origins. Moreover, the dying cells resulted from our chimeras exhibited potent immunogenicity in vitro, and elicited more efficiently anti-tumor immunity in vivo in comparison with those dying from Verteporfin. Our approach therefore provides a novel method to dysfunction GPX4 based on noncovalent binding and specifically trigger immunogenic ferroptosis, which may boost the development of triggering ferroptosis as a potential strategy in cancer immunotherapy

Molecular characters and different expression of WRKY1 gene from Gossypium barbadense L. and Gossypium hirsutum L.

Cotton is one of the most important economic crops in the world. Gossypium barbadense L. has higher resistance to Verticillium wilt than Gossypium hirsutum L. In the present study, seedlings of Pima90-53 (G. barbadense) had better growth performance than those of CRI8 (G. hirsutum) inoculated with Verticillium dahliae. WRKY1 genomic DNA of Pima90-53 and CRI8 were isolated (GbWRKY1 and GhWRKY1) and predicted to include three introns which were 289, 92, 87 bp and 286, 92, 87 bp in length, respectively. Compared with the DNA sequence of GbWRKY1, GhWRKY1 had a 13-base deletion in exon 4, which resulted in premature termination of translation. It was predicted that the GbWRKY1 and GhWRKY1 proteins contain two WRKY domains and zinc-finger motifs belonging to group I WRKY proteins. Two promoters, located 1745 bp and 1738 bp upstream of GbWRKY1 and GhWRKY1, were cloned and predicted to contain important regulatory elements (TATA-box, CAAT-box and pathogen/elicitor-related elements). Interestingly, compared with GbWRKY1, the GhWRKY1 promoter lacked an ethylene-responsive element (ERE) component. The relative expression of GbWRKY1, too, was higher than that of GhWRKY1 after V. dahliae and ACC (1-aminocyclopropane-1-carboxylic acid) induction. The results suggest that the difference in the promoter sequence could probably be one of the reasons that lead to different expression patterns and resistance to Verticillium wilt in Pima90-53 and CRI8

Synthesis of Chamaecypanone C Analogues from <i>in Situ</i>-Generated Cyclopentadienones and Their Biological Evaluation

A rhodium-catalyzed dehydrogenation protocol for the conversion of 3,5-diarylcyclopentenones to the corresponding 2,4-diarylcyclopentadienones has been developed. With this protocol, analogues of the cytotoxic agent chamaecypanone C have been synthesized <i>via</i> Diels–Alder cycloaddition between the cyclopentadienones and <i>in situ</i>-generated <i>o</i>-quinols. Biological evaluation of these analogues revealed a compound with higher activity as a microtubule inhibitor and cytotoxic agent in comparison with the parent structure