Spectroscopic studies of the interaction between phosphorus heterocycles and cytochrome P450

P450 fatty acid decarboxylase Ole T from Staphylococcus aureus(Ole TSA)is a novel cytochrome P450 enzyme that catalyzes the oxidative decarboxylation of fatty acids to yield primarily terminal alkenes and CO_(2) or minor a-andβ-hydroxylated fatty acids as side-products.In this work,the interactions between a series of cycloalkyl phosphorus heterocycles(CPHs)and Ole TSAwere investigated in detail by fluorescence titration experiment,ultraviolet-visible(UV-vis)and31 P NMR spectroscopies.Fluorescence titration experiment results clearly showed that a dynamic quenching occurred when CPH-6,a representative CPHs,interacted with Ole TSAwith a binding constant value of 15.2×104 M-1 at 293 K.The thermodynamic parameters(ΔH,ΔS andΔG)showed that the hydrogen bond and van der Waals force played major roles in the interaction between Ole TSAand CPHs.The UV-vis and31 P NMR studies indicated the penetration of CPH-6 into the interior environment of Ole TSA,which greatly affects the enzymatic activity of Ole TSA.Therefore,our study revealed an effective way to use phosphorus heterocyclic compounds to modulate the activity of cytochrome P450 enzymes.

Anti-catalytic and zincophilic layers integrated zinc anode towards efficient aqueous batteries for ultra-long cycling stability

Aqueous zinc-based battery is usually plagued by serious dendrites and side reactions including Zn corrosion and water decomposition on the anode.To address the drawbacks,constructing coating layers with high conductivity and anti-catalytic effects on hydrogen evolution reaction has been considered as an efficient strategy.Herein,cheap and abundant twodimensional(2D)conductive graphite(KS-6)coating layer with high electronic conductivity(~106 S·m^(−1))could directly form strong bonding with Zn foil due to high zincophilicity,which correspondingly protects Zn metal from liquid electrolyte to inhibit parasitic hydrogen evolution and guide uniform Zn electrodeposition during cycling.The KS-6 layer owns a profitable charge redistribution effect to endow Zn anode with a lower nucleation energy barrier and a more uniformly distributed electric field compared with bare Zn.Therefore,such integrated Zn anode exhibits low voltage hysteresis(~38 mV)and excellent cycling stability with dendrite-free behaviors(1 mA·cm^(−2)and 2 mAh·cm^(−2))over 2,000 h,far outperforming many reported Zn metal anodes in aqueous systems.Encouragingly,in light of the superior Zn@KS-6 anode,VNOx powders and Prussian blue analogs Mn_(2)Fe(CN)_(6)are applied as the cathode materials to assemble full batteries,which show remarkable cycling stabilities and high Coulombic efficiencies(CEs)over 200 cycles with capacity retention of 81.5%for VNOx//Zn@KS-6 battery and over 400 cycles with capacity retention of 94.6%for Mn_(2)Fe(CN)_(6)//Zn@KS-6 battery,respectively.