Boosting CO2 Conversion with Terminal Alkynes by Molecular Architecture of Graphene Oxide-Supported Ag Nanoparticles

Confining SnS2 Ultrathin Nanosheets in Hollow Carbon Nanostructures for Efficient Capacitive Sodium Storage

Functional Two- and Three-Dimensional Architectures of Immobilized Metal Nanoparticles

Quantifying Electrocatalytic Reduction of CO2 on Twin Boundaries

Visible-light photoredox-catalyzed selective carboxylation of C(sp3)−F bonds with CO2

Liquid fuel synthesis via CO2 hydrogenation by coupling homogeneous and heterogeneous catalysis

Uncovering strong π-metal interactions on Ag and Au nanosurfaces under ambient conditions via in-situ surface-enhanced Raman spectroscopy

Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

Integration of carbon capture with utilization technologies can lead the way to a net-zero carbon economy. Nevertheless, direct chemical conversion of chemically captured CO2 remains challenging due to its thermodynamic stability. Here, we demonstrate CO2 capture from flue gas/air and its direct conversion into syngas under solar irradiation without any externally applied voltage. The system captures CO2 with an amine/hydroxide solution and photoelectrochemically converts it into syngas (CO:H2 1:2 (concentrated CO2), 1:4 (simulated flue gas), and 1:30 (air)) using a perovskite-based photocathode with an immobilized molecular Co-phthalocyanine catalyst. At the anode, plastic-derived ethylene glycol is oxidized into glycolic acid over a Cu26Pd74 alloy catalyst. The overall process uses flue gas/air as carbon source and discarded plastic waste as electron donor, opening avenues for integrated carbon-neutral/negative solar fuel and waste upcycling technologies.

Biotin is a water-soluble vitamin that functions as a prosthetic group in carboxylation reactions. In addition to its role as a cofactor, biotin has multiple roles in gene regulation. We analyzed biotin effects on gene expression in the yeast Saccharomyces cerevisiae and demonstrated by microarray, Northern, and Western analyses that all yeast genes encoding proteins involved in biotin metabolism are up-regulated following biotin depletion. Many of these genes contain a palindromic promoter element that is necessary and sufficient for mediating the biotin response and functions as an upstream-activating sequence. Mutants lacking the plasma membrane biotin transporter Vht1p display constitutively high expression levels of biotin-responsive genes. However, they react normally to biotin precursors that do not require Vht1p for uptake. The biotin-like effect of precursors with regard to gene expression requires their intracellular conversion to biotin. This demonstrates that Vht1p does not act as a sensor for biotin and that intracellular biotin is crucial for gene expression. Mutants with defects in biotin-protein ligase, similar to vht1delta mutants, also display aberrantly high expression of biotin-responsive genes. Like vht1delta cells, they have reduced levels of protein biotinylation, but unlike vht1delta mutants, they possess normal levels of free intracellular biotin. This indicates that free intracellular biotin is irrelevant for gene regulation and identifies biotin-protein ligase as an important element of the biotin-sensing pathway in yeast.

The sequences classified as genes for various ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (RuBisCO)-like proteins (RLPs) are widely distributed among bacteria, archaea, and eukaryota. In the phylogenic tree constructed with these sequences, RuBisCOs and RLPs are grouped into four separate clades, forms I-IV. In RuBisCO enzymes encoded by form I, II, and III sequences, 19 conserved amino acid residues are essential for CO(2) fixation; however, 1-11 of these 19 residues are substituted with other amino acids in form IV RLPs. Among form IV RLPs, the only enzymatic activity detected to date is a 2,3-diketo-5-methylthiopentyl 1-phosphate (DK-MTP-1-P) enolase reaction catalyzed by Bacillus subtilis, Microcystis aeruginosa, and Geobacillus kaustophilus form IV RLPs. RLPs from Rhodospirillum rubrum, Rhodopseudomonas palustris, Chlorobium tepidum, and Bordetella bronchiseptica were inactive in the enolase reaction. DK-MTP-1-P enolase activity of B. subtilis RLP required Mg(2+) for catalysis and, like RuBisCO, was stimulated by CO(2). Four residues that are essential for the enolization reaction of RuBisCO, Lys(175), Lys(201), Asp(203), and Glu(204), were conserved in RLPs and were essential for DK-MTP-1-P enolase catalysis. Lys(123), the residue conserved in DK-MTP-1-P enolases, was also essential for B. subtilis RLP enolase activity. Similarities between the active site structures of RuBisCO and B. subtilis RLP were examined by analyzing the effects of structural analogs of RuBP on DK-MTP-1-P enolase activity. A transition state analog for the RuBP carboxylation of RuBisCO was a competitive inhibitor in the DK-MTP-1-P enolase reaction with a K(i) value of 103 mum. RuBP and d-phosphoglyceric acid, the substrate and product, respectively, of RuBisCO, were weaker competitive inhibitors. These results suggest that the amino acid residues utilized in the B. subtilis RLP enolase reaction are the same as those utilized in the RuBisCO RuBP enolization reaction.

Synthesis of Large-Area Single-Crystal Graphene

Voltage-gated potassium (K(V)) channels, such as KCNQ1 (K(V)7.1), are modulated by accessory subunits and regulated by intracellular second messengers. Accessory subunits belonging to the KCNE family exert diverse functional effects on KCNQ1, have been implicated in the pathogenesis of various genetic disorders of heart rhythm, and contribute to transducing intracellular signaling events into changes in K(V) channel activity. We investigated the interactions between calmodulin (CaM), the ubiquitous Ca(2+)-transducing protein that binds and confers Ca(2+) sensitivity to the biophysical properties of KCNQ1, and KCNE4. These studies were motivated by the observed similarities between the suppression of KCNQ1 function by pharmacological disruption of KCNQ1-CaM interactions and the effects of KCNE4 co-expression on the channel. We determined that KCNE4, but not KCNE1, can biochemically interact with CaM and that this interaction is Ca(2+)-dependent and requires a tetraleucine motif in the juxtamembrane region of the KCNE4 C terminus. Furthermore, disruption of the KCNE4-CaM interaction either by mutagenesis of the tetraleucine motif or by acute Ca(2+) chelation impairs the ability of KCNE4 to inhibit KCNQ1. Our findings have potential relevance to KCNQ1 regulation both by KCNE accessory subunits and by an important intracellular signaling molecule.

Ni-catalyzed enantioselective [2 + 2 + 2] cycloaddition of malononitriles with alkynes

Variants in Autophagy Genes Affect Susceptibility to Both Crohn's Disease and Helicobacter pylori Infection

Selective C-C Bond Scission of Ketones via Visible-Light-Mediated Cerium Catalysis