Effects of Se substitution and transition metal doping on the electronic and magnetic properties of a MoSxSe2-x/h-BN heterostructure.

The van der Waals heterostructures created by stacking two monolayer semiconductors have been rapidly developed experimentally and exhibit various unique physical properties. In this work, we investigate the effects of Se atom substitution and 3d-TM atom doping on the structural, electronic, and magnetic properties of the MoSe2/h-BN heterostructure, by using first-principles calculations based on density functional theory (DFT). It is found that Se atom substitution could considerably enhance the band gaps of MoSe2/h-BN heterostructures. With an increase in the substitution concentration, the energy band changes from an indirect to a direct band gap when the substitution concentration exceeds a critical value. For 3d-TM atom doping, it is shown that V-, Mn-, Fe-, and Co-doped systems exhibit a half-metallic state and magnetic behavior, while there is no spin polarization in the Ni-doped case. The results provide a theoretical basis for the development of diluted magnetic semiconductors and spin devices based on the MoSxSe2-x/h-BN heterostructure.

Investigation of an "alternate water supply system" in enzymatic hydrolysis in the processive endocellulase Cel7A from Rasamsonia emersonii by molecular dynamics simulation.

Cel7A from Rasamsonia emersonii is one of the processive endocellulases classified under family 7 glycoside hydrolase. Molecular dynamics simulations were carried out to obtain the optimized sliding and hydrolyzing conformations, in which the reducing ends of sugar chains are located on different sites. Hydrogen bonds are investigated to clarify the interactions between protein and substrate in either conformation. Nine hydrogen bonding interactions are identified in the sliding conformation, and six similar interactions are also found correspondingly in the hydrolyzing conformation. In addition, four strong hydrophobic interactions are also determined. The domain cross-correlation map analysis shows movement correlation of protein including autocorrelation between residues. The root mean square fluctuations analysis represents the various flexibilities of different fragment in the two conformations. Comparing the two conformations reveals the water-supply mechanism of selective hydrolysis of cellulose in Cel7A. The mechanism can be described as follow. When the reducing end of substrate slides from the unhydrolyzing site (sliding conformation) to the hydrolyzing site (hydrolyzing conformation), His225 is pushed down and rotated, the rotation leads to the movement of Glu209 with the interstrand hydrogen bonding in ß-sheet. It further makes Asp211 close to the hydrolysis center and provides a water molecule bounding on its carboxyl in the previous unhydrolyzing site. After the hydrolysis takes place and the product is excluded from the enzyme, the Asp211 comes back to its initial position. In summary, Asp211 acts as an elevator to transport outer water molecules into the hydrolysis site for every other glycosidic bond.

Insight into the interactive residues between two domains of human somatic Angiotensin-converting enzyme and Angiotensin II by MM-PBSA calculation and steered molecular dynamics simulation.

Angiotensin-converting enzyme (ACE), a membrane-bound zinc metallopeptidase, catalyzes the formation of Angiotensin-II (AngII) and the deactivation of bradykinin in the renin-angiotensin-aldosterone and kallikrein-kinin systems. As a hydrolysis product of ACE, AngII is regarded as an inhibitor and displays stronger competitive inhibition in the C-domain than the N-domain of ACE. However, the AngII binding differences between the two domains and the mechanisms behind AngII dissociation from the C-domain are rarely explored. In this work, molecular docking, Molecular Mechanics/Poisson-Boltzmann Surface Area calculation, and steered molecular dynamics (SMD) are applied to explore the structures and interactions in the binding or unbinding of AngII with the two domains of human somatic ACE. Calculated free energy values suggest that the C-domain-AngII complex is more stable than the N-domain-AngII complex, consistent with available experimental data. SMD simulation results imply that electrostatic interaction is dominant in the dissociation of AngII from the C-domain. Moreover, Gln106, Asp121, Glu123, and Tyr213 may be the key residues in the unbinding pathway of AngII. The simulation results in our work provide insights into the interactions between the two domains of ACE and its natural peptide inhibitor AngII at a molecular level. Moreover, the results provide theoretical clues for the design of new inhibitors.

Immunotherapeutic Effects of Dendritic Cells Pulsed with a Coden-optimized HPV 16 E6 and E7 Fusion Gene in Vivo and in Vitro.

BACKGROUND: Cervical cancer is the second most common cause of cancer related death of women. Persistent HPV infection, especially with high-risk types such as HPV16 and HPV18, has been identified to be the primary cause of cervical cancer. E6 and E7 are the major oncoproteins of high-risk HPVs, which are expressed exclusively in HPV infected tissues, and thereby represent ideal therapeutic targets for immunotherapy of cervical cancer. MATERIALS AND METHODS: In this work, we used recombinant adenovirus expressing coden-optimized HPV16 E6 and E7 fusion protein (Ad-ofE6E7) to prime dendritic cells (DC-ofE6E7), to investigate the ability of primed DC vaccine in eliciting antitumor immunity in vitro and vivo. RESULTS: Our results indicated that DC-ofE6E7 vaccine co-culturing with splenocytes could strongly induce a tumor-specific cytotoxic T lymphocyte (CTL) response and kill the TC-1 cells effectively in vitro. Moreover, DC-ofE6E7 vaccine induced protective immunity against the challenge of TC-1 cancer cells in vivo. CONCLUSIONS: The results suggested that the HPV16 ofE6E7 primed DC vaccine has potential application for cervical cancer immunotherapy.

[Effects of electroacupuncture on expression of Abeta positive cells of the hippocampus and SOD activity in rats with streptozocin-Alzheimer's disease].

OBJECTIVE: To investigate the possible mechanism of the electroacupuncture for improvement of learning and memory in rats of Alzheimer's disease (AD). METHODS: Sixty Wistar rats were randomly divided into a normal group, a normal saline group, a model group, a western medication group and an electroacupuncture group, 12 rats in each group. The AD rat model was established by injecting Streptozocin (STZ) into lateral cerebral ventricle, except the rats in the normal saline group injecting Normal Saline with the same dose and in normal group with no injection. The western medication group was treated with intragastric administration of Memantine, and in the electroacupuncture group, the electroacupuncture was given at "Baihui" (GV 20), "Dazhui" (CV 14), "Taixi" (KI 3), "Shenshu" (BL 23), "Zusanli" (ST 36), once each day, 7 days for a course, and lasted for 4 courses. The other three groups were fed in routine way and without any treatment. The learning and memory ability was assessed by Morris water maze and the expression of Abeta positive cells of the hippocampus and superoxide dismutase (SOD) activity were determined by immunohistochemistry and visible spectrophotometer colorimetry. RESULTS: Compared with the normal group and the normal saline group, the Abeta protein expression was significantly increased in the model group (both P < 0.01), and the SOD activity was obviously decreased (both P < 0.01). After treatment, as compared with the model group, the Abeta protein expression was significantly decreased (both P < 0.01), and the SOD activity was obviously increased (both P < 0.01) in the electroacupuncture group and western medication group. CONCLUSION: Electroacupuncture treatment can reduce the Abeta protein expression and increase the SOD activity of the hippocampus so as to improve learning and memory ability in the AD rats.