Insight on Performance Degradation of Phthalocyanine Cobalt-Based Gas Diffusion Cathode for Carbon Dioxide Electrochemical Reduction

Phthalocyanine is a type of non-noble metal electrocatalyst that efficiently and selectively produces CO from CO2. Herein, we studied the durability of a cobalt phthalocynine (CoPc)-based gas diffusion electrode (GDE) in a flow cell. This is the first report on the degradation mechanism of the CoPc-based GDE for CO2 electrochemical reduction. Leaching of CoPc and demetalation of phthalocyanine are observed, and the interaction between CoPc and carbon black becomes weaker after a durability test. More seriously, part of the micropores of the GDE which act as mass transfer channels of reactants and products collapse, and the hydrophobicity of the catalyst layer of the GDE is almost destroyed. This means that the mass transfer properties of the GDE undergo tremendous changes. To enhance the durability of CoPc-based GDEs, work to prevent the deactivation of the catalyst and improve the solidity of the microstructure of GDEs should be done

Structure-Based Design and Screen of Novel Inhibitors for Class II 3-Hydroxy-3-methylglutaryl Coenzyme A Reductase from Streptococcus Pneumoniae

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) is a primary target in the current clinical treatment of hypercholesterolemia with specific inhibitors of “statin” family. Statins are excellent inhibitors of the class I (human) enzyme but relatively poor inhibitors of the class II enzyme, which are well-known as a potential target to discover drugs fighting against the invasive diseases originated from S. pneumoniae. However, no significantly effective inhibitors of class II HMGR have been reported so far. In the present study, the reasonable three-dimensional (3D) structure of class II HMGR from S. pneumoniae (SP-HMGR-II) was built by Swissmodel. On the basis of the modeling 3D structure in “close” flap domain form, several novel potential hit compounds out of SPECs database were picked out by using structure-based screening strategy. Especially the compounds <b>4</b>, <b>3</b>, and <b>11</b> exhibit highly inhibitory activities, with IC₅₀ values of 11.5, 18.5, and 18.1 μM, respectively. Furthermore, the hit compounds were chosen as probe molecules, and their probable interactions with the corresponding individual residues have been examined by jointly using the molecular docking, site-directed mutagenesis, enzymatic assays, and fluorescence spectra, to provide an insight into a new special binding-model located between the HMG-CoA and NADPH pockets. The good agreement between theoretical and experimental results indicate that the modeling strategies and screening processes in the present study are very likely to be a promising way to search novel lead compounds with both structural diversity and high inhibitory activity against SP-HMGR-II in the future