Molecular mechanism by which spider-driving peptide potentiates coagulation factors.

Hemostasis is a crucial process that quickly forms clots at injury sites to prevent bleeding and infections. Dysfunctions in this process can lead to hemorrhagic disorders, such as hemophilia and thrombocytopenia purpura. While hemostatic agents are used in clinical treatments, there is still limited knowledge about potentiators targeting coagulation factors. Recently, LCTx-F2, a procoagulant spider-derived peptide, was discovered. This study employed various methods, including chromogenic substrate analysis and dynamic simulation, to investigate how LCTx-F2 enhances the activity of thrombin and FXIIa. Our findings revealed that LCTx-F2 binds to thrombin and FXIIa in a similar manner, with the N-terminal penetrating the active-site cleft of the enzymes and the intermediate section reinforcing the peptide-enzyme connection. Interestingly, the C-terminal remained at a considerable distance from the enzymes, as evidenced by the retention of affinity for both enzymes using truncated peptide T-F2. Furthermore, results indicated differences in the bonding relationship of critical residues between thrombin and FXIIa, with His13 facilitating binding to thrombin and Arg7 being required for binding to FXIIa. Overall, our study sheds light on the molecular mechanism by which LCTx-F2 potentiates coagulation factors, providing valuable insights that may assist in designing drugs targeting procoagulation factors.

Hemiboea suiyangensis (Gesneriaceae): a new species from Guizhou, China.

The limestone areas in south China are a major biodiversity hotspot for terrestrial biomes. Hemiboea, with 34 species and 5 varieties, mainly distributed in south China, is one of the characteristic plant groups in limestone areas. Hemiboea suiyangensis, a new species of Gesneriaceae from limestone areas in Guizhou, China, is described and illustrated. The new species is easily distinguished from other Hemiboea species by having an oblique-infundibular corolla with an abaxially gibbous swelling on the upper half of the tube and with a densely villose throat and lower lobes. Hemiboea suiyangensis is similar to H. omeiensis W. T. Wang in the shape of the leaf blade, but differs from the latter by the shape of the petiole, involucre, calyx and corolla and the colour of the corolla. The conservation status of this species is considered to be "Critically Endangered" (CR) according to IUCN Red List Criteria.

N-heterocyclic carbene-palladium(II)-1-methylimidazole complex catalyzed α-arylation reactions of tetralones with aryl chlorides and further transformation of the products.

NHC-Pd(II)-Im complex 1 has proven to be an efficient catalyst in the reaction between tetralones 2 and aryl chlorides 3, giving the α-arylated tetralones 4 in good to high yields. In addition, if the above reaction mixture was exposed to air at room temperature for another 3 h, the normal α-arylated products 4 can be fully oxidized to 2-aryl-2'-hydroxytetralones 6 in good yields in a one-pot procedure. Furthermore, if the reaction mixture containing the oxidized products 6 was treated with TsOH/toluene solution under reflux for 19 h, the final aromatized products, 2-aryl-naphthalen-1-ols 5 can be achieved in acceptable to moderate yields. All reactions can tolerate various substituents on the tetralones 2 and aryl chlorides 3, thus giving an efficient method for the α-arylation of tetralones and further transformation of the products, and also enriching the applications of NHC-Pd(II) complexes in organic synthesis.