Chloride-selective transmembrane carriers or channels might have possible uses in treating channelopathies or cancers. While chloride carriers have been extensively investigated, the corresponding chloride channels have remained limitedly studied. Moreover, all hitherto reported channel systems lack clearly definable and readily modifiable positions in their structures for the reliable construction and combinatorial optimization of their ion transport properties. As a result, the existing channels are limited by their large molecular weight, weak activity or low anion selectivity. In this report, we describe a readily accessible and robust monopeptide-based scaffold for the reliable construction of halogen bond-mediated artificial anion channels via directional assembly of electron-deficient iodine atoms, which create a transmembrane pathway for facilitating anion transport. The high intrinsic modularity of the backbone of the scaffold, which enables the rapid and combinatorial optimization of the transport activity and selectivity of channels, effectively delivers a highly active chloride channel A10. Such high activity in chloride transport subsequently leads to an excellent IC50 value of 20 μM toward inhibiting the growth of human breast cancer cells (BT-474), an anticancer activity that is even higher than that of the well-known anticancer agent cisplatin.
Transition metal phosphides (TMPs) have been proven to act as highly active catalysts for the hydrogen evolution reaction (HER). Recently, single-phase ternary NiCoP electrocatalysts have been shown through experiments to display remarkable catalytic activity for the HER during water splitting. But, the inherent mechanism is not well understood. Herein, the HER activity of NiCoP with low-Miller-index facets, including (111), (100), (001)-NiP-t, and (001)-CoP-t, was systematically investigated using periodic density functional theory (DFT). The calculated Gibbs free energy of hydrogen adsorption (ΔGH) values reveal that all calculated facets have good catalytic activity for the HER. The (111) facet with the lowest surface energy in a vacuum has optimal ΔGH values close-to-zero for a range of hydrogen coverage. Ab initio thermodynamic analysis of hydrogen coverage was conducted to obtain the stabilities of surfaces, which follow the trend: (111) > (001)-CoP-t > (100) > (001)-NiP-t at 1 atm H2 and 298 K. We hope that this work can shed new light on further understanding the HER in relation to NiCoP and can give guidance for the design and synthesis of transition bimetal phosphide-based catalysts.
Plants utilize a UV-B (280 to 315 nm) photoreceptor UVR8 (UV RESISTANCE LOCUS 8) to sense environmental UV levels and regulate gene expression to avoid harmful UV effects. Uniquely, UVR8 uses intrinsic tryptophan for UV-B perception with a homodimer structure containing 26 structural tryptophan residues. However, besides 8 tryptophans at the dimer interface to form two critical pyramid perception centers, the other 18 tryptophans’ functional role is unknown. Here, using ultrafast fluorescence spectroscopy, computational methods and extensive mutations, we find that all 18 tryptophans form light-harvesting networks and funnel their excitation energy to the pyramid centers to enhance light-perception efficiency. We determine the timescales of all elementary tryptophan-to-tryptophan energy-transfer steps in picoseconds to nanoseconds, in excellent agreement with quantum computational calculations, and finally reveal a significant leap in light-perception quantum efficiency from 35% to 73%. This photoreceptor is the first system discovered so far, to be best of our knowledge, using natural amino-acid tryptophans to form networks for both light harvesting and light perception.