Structure-based stabilization of protein−protein interactions (PPIs) is a promising strategy for drug discovery. However, this approach has mainly focused on the stabilization of native PPIs, and non-native PPIs have received little consideration. Here, we identified a non-native interaction interface on the three-dimensional dimeric structure of the N-terminal domain of the MERS-CoV nucleocapsid protein (MERS-CoV N-NTD). The interface formed a conserved hydrophobic cavity suitable for targeted drug screening. By considering the hydrophobic complementarity during the virtual screening step, we identified 5benzyloxygramine as a new N protein PPI orthosteric stabilizer that exhibits both antiviral and N-NTD protein-stabilizing activities. X-ray crystallography and small-angle X-ray scattering showed that 5-benzyloxygramine stabilizes the N-NTD dimers through simultaneous hydrophobic interactions with both partners, resulting in abnormal N protein oligomerization that was further confirmed in the cell. This unique approach based on the identification and stabilization of non-native PPIs of N protein could be applied toward drug discovery against CoV diseases.

Cardiotoxin III (CTX III), a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom, has been reported to have anticancer activity.

No abstract

No abstract

Background: This study investigated whether a hyaluronic acid–povidone-iodine compound can enhance diabetic wound healing. Methods: A dorsal skin defect (6 × 5 cm) in a streptozotocin-induced diabetes rodent model was used. Seventy male Wistar rats were divided into seven groups: I, normal control; II, diabetic control, no treatment; III, diabetic rats, lower molecular weight (100 kDa) hyaluronic acid; IV, rats, higher molecular weight (1000 kDa) hyaluronic acid; V, rats, 0.1% povidone-iodine; VI, rats, lower molecular weight hyaluronic acid plus povidone-iodine; and VII, rats, higher molecular weight hyaluronic acid plus povidone-iodine. Histologic examination was performed with hematoxylin and eosin staining. CD45, Ki-67, prolyl 4-hydroxylase, and vascular endothelial growth factor were evaluated with immunohistochemical staining. Results: Compared with the control, higher molecular weight hyaluronic acid plus povidone-iodine–treated rats had significantly reduced wound area (p < 0.001). Higher molecular weight hyaluronic acid plus povidone-iodine increased wound healing time when compared with higher molecular weight hyaluronic acid, povidone-iodine, or lower molecular weight hyaluronic acid plus povidone-iodine. Histology revealed significantly increased neovessels and suppressed inflammatory response in the higher molecular weight hyaluronic acid plus povidone-iodine group when compared with the control group. Immunohistochemical staining revealed significantly increased Ki67, prolyl 4-hydroxylase, and vascular endothelial growth factor expression, and suppressed CD45 expression in the higher molecular weight hyaluronic acid plus povidone-iodine group when compared with the other groups. Conclusion: Higher molecular weight hyaluronic acid plus povidone-iodine complex dressing significantly facilitated diabetic wound healing via increasing neovascularization and tissue regeneration and suppressing a proinflammatory response.

1. Cardiotoxin (CTX) III is a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom. This is the first report on the mechanism of the anticancer effect of CTX III on human leukaemia K562 cells. 2. Cardiotoxin III was found to inhibit the growth of K562 cells in a time- and dose-dependent manner, with an IC(50) value of 1.7 mug/mL, and displayed several features of apoptosis, including apoptotic body formation, an increase in the sub-G(1) population, DNA fragmentation and poly (ADP-ribose) polymerase (PARP) cleavage. 3. Investigation of the mechanism of CTX III-induced apoptosis revealed that treatment of K562 cells with CTX III resulted in the loss of mitochondrial membrane potential, cytochrome c release from mitochondria into the cytosol and activation of caspase-9 and caspase-3 and the subsequent cleavage of the caspase-3 substrate PARP; however, CTX III did not generate reactive oxygen species (ROS). 4. Taken together, the results indicate that CTX III induces apoptosis in K562 cells through an ROS-independent mitochondrial dysfunction pathway.

Cardiotoxin III (CTX III) is a basic polypeptide with 60 amino acid residues isolated from Naja naja atra venom. This is the first report on the mechanism of the anticancer effect of CTX III in human colorectal cancer Colo205 cells. 2. Cardiotoxin III-induced Colo205 cell apoptosis was confirmed by DNA fragmentation (DNA ladder and sub-G1 formation) with an IC(50) of 4 mg/mL at 48 h. 3. Further mechanistic analysis demonstrate that CTX III induced the loss of mitochondrial membrane potential (Dym), cytochrome c release from mitochondria into the cytosol and activation of capase-9, caspase 3, as well as markedly enhancing the expression of Bax, but not Bcl-2, protein in the cells. Moreover, the CTX III-induced apoptosis was significantly blocked by the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone. 4. However, CTX III did not generate the formation of reactive oxygen species and anti-oxidants, including N-acetylcysteine, and catalase could not block CTX III-induced apoptosis in the Colo205 cells. 5. Taken together, these results suggest that CTX III may induce apoptosis through a mitochondrial- and caspase-dependent mechanism and alteration of Bax/Bcl-2 ratio in human colorectal Colo205 cancer cells.

No abstract