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The Anderson localization phase transition in the Aubry-André-Harper (AAH) model with p-wave superconducting (SC) pairing is numerically investigated by suddenly changing the on-site potential from zero to various finite values which fall into the extended, critical and localized phase regimes shown in this model. The time evolution of entanglement entropy (EE), mean width of wave packets and Loschmidt echo of the system exhibit distinct but consistent dynamical signatures in those three phases. Specifically, the EE grows as a power function of time with the exponent of which varies in the extended phase but keeps almost unchanged in the critical phase for different quench parameters. However, if the system is in the localized phase after a quench, the EE grows much slower and will soon get saturated. The time-dependent width of wave packets in the system shows similar behaviors as the EE. In addition, from the perspective of the dynamical phase transition, we find that the Loschmidt echo oscillates and always keeps finite when the system is quenched in the extended phase. In contrast, in the critical or localized phase, the echo will reach to zero at some time intervals or will decay almost to zero after a long-time evolution. The universal features of these quantities in the critical phase of the system with various SC pairing amplitudes are also observed. [ABSTRACT FROM AUTHOR]

We propose a new scheme of realizing spin-polarized currents in a double quantum dot system. In the presence of Rashba spin-orbit coupling interactions and different Zeeman splittings of each quantum dot, the currents are spin-polarized. The polarization can be controlled by tuning the strength of Rashba spin-orbit coupling and external magnetic fields, which can produce nearly 100% spin-polarized currents. Furthermore, we explain and analyze the mechanism of the strongly spin-polarized currents. Lastly we give two phase diagrams to display our results. [ABSTRACT FROM AUTHOR]

Tyrosinase inhibition studies are needed due to the agricultural and medicinal applications. For probing effective inhibitors of tyrosinase, a combination of computational prediction and enzymatic assay via kinetics were important. We predicted the 3D structure of tyrosinase from Agaricus bisporus, used a docking algorithm to simulate binding between tyrosinase and terephthalic acid (TPA) and studied the reversible inhibition of tyrosinase by TPA. Simulation was successful (binding energies for Autodock4 = −1.54 and Fred2.0 = −3.19 kcal/mol), suggesting that TPA interacts with histidine residues that are known to bind with copper ions at the active site. TPA inhibited tyrosinase in a mixed-type manner with a K = 11.01 ± 2.12 mM. Measurements of intrinsic and ANS-binding fluorescences showed that TPA induced no changes in tertiary structure. The present study suggested that the strategy of predicting tyrosinase inhibition based on hydroxyl groups and orientation may prove useful for screening of potential tyrosinase inhibitors. [ABSTRACT FROM AUTHOR]

Superoxide dismutase (SOD, EC 1.15.1.1) plays an important antioxidant defense role in skins exposed to oxygen. We studied the inhibitory effects of Al3+ on the activity and conformation of manganese-containing SOD (Mn-SOD). Mn-SOD was significantly inactivated by Al3+ in a dose-dependent manner. The kinetic studies showed that Al3+ inactivated Mn-SOD follows the first-order reaction. Al3+ increased the degree of secondary structure of Mn-SOD and also disrupted the tertiary structure of Mn-SOD, which directly resulted in enzyme inactivation. We further simulated the docking between Mn-SOD and Al3+ (binding energy for Dock 6.3: -14.07 kcal/mol) and suggested that ASP152 and GLU157 residues were predicted to interact with Al3+, which are not located in the Mn-contained active site. Our results provide insight into the inactivation of Mn-SOD during unfolding in the presence of Al3+ and allow us to describe a ligand binding via inhibition kinetics combined with the computational prediction. [ABSTRACT FROM AUTHOR]

Acrylamide is widely used worldwide in industry and it can also be produced by the cooking and processing of foods. It is harmful to human beings, and human brain CK (HBCK) has been proposed to be one of the important targets of acrylamide. In this research, we studied the effects of acrylamide on HBCK activity, structure and the potential binding sites. Compared to CKs from rabbit, HBCK was fully inactivated at several-fold lower concentrations of acrylamide, and exhibited distinct properties upon acrylamide-induced inactivation and structural changes. The binding sites of acrylamide were located at the cleft between the N- and C-terminal domains of CK, and Glu232 was one of the key binding residues. The effects of acrylamide on CK were proposed to be isoenzyme- and species-specific, and the underlying molecular mechanisms were discussed. [ABSTRACT FROM AUTHOR]

Abstract  We studied the effect of cysteine modification on creatine kinase (CK) aggregation as well as the kinetics of the process. We found that CK aggregation was modulated by different pH conditions in the presence of Zn2+, which is a CK aggregation trigger. The CK aggregation followed first-order kinetics, and this was effectively suppressed in acidic conditions. Even under the acidic condition, cysteine modification at the active site with using 5,5′-dithiobis-2-nitrobenzoic acid (DTNB) induced conspicuous aggregation in a dose-dependent manner. This aggregation process is directly related with decreasing the change of transition free-energy (ΔΔG AG ). When dithiothreitol (DTT) was applied to the reaction system, the aggregates were significantly reduced: DTT treatment can fully reactivate (higher than 80%) the inactive CK that was separated from CK aggregates, whereas CK was completely inactivated by Zn2+ and DTNB. Some added osmolytes such as glycine and proline were able to successfully block CK aggregation by increasing the ΔΔG AG as well as by suppressing the hydrophobic CK surface. Our study suggests the effect of cysteine modification on the unfavorable aggregation of CK and on the aggregation process that followed first-order kinetics with the accompanying changes of transitional free energy and disruptions of the hydrophobic surface. We also demonstrate the successful protocol to block the aggregation. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue including one on the roles of matrix metalloproteinases (MMPs), one on the mechanisms of autotaxin in the treatment of melanoma and another one on the inhibition kinetics for tyrosinase.