Bimetallic Cooperativity in Proton Reduction with an Amido‐Bridged Cobalt Catalyst

The bimetallic catalyst [CoII2(L1)(bpy)2]ClO4 (1), in which L1 is an [NN′2O2] fused ligand, efficiently reduced H+ to H2 in CH3CN in the presence of 100 equiv of HOAc with a turnover number of 18 and a Faradaic efficiency of 94 % after 3 h of bulk electrolysis at −1.6 V (vs. Ag/AgCl). This observation allowed the proposal that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co−Namido−Co environment offered by L1. Experimental results revealed that the parent [CoIICoII] complex undergoes two successive metal‐based 1 e− reductions to generate the catalytically active species [CoICoI], and DFT calculations suggested that addition of a proton to one CoI triggers a cooperative 1 e− transfer by each of these CoI centers. This 2 e− transfer is an alternative route to generate a more reactive [CoII(CoII−H−)] hydride, thus avoiding the CoIII−H− required in monometallic species. This [CoII(CoII−H−)] species then accepts another H+ to release H2

Visible and Infrared Spectroelectrochemistry of Cobalt Porphinones and Porphinediones

The visible and infrared spectroelectrochemistry of the redox chemistry of CoII–porphinone complexes were examined and compared with similar studies of the respective iron complexes. Cobalt(II) porphinone complexes undergo a one-electron reduction and two one-electron oxidations within the potential region that was studied in this work. The one electron spectroelectrochemical reduction of CoII(P) (P = octaethylporphyrin (OEP), octaethylporphinone (OEPone), and octaethylporphinedione (OEPdione)) were studied using visible spectroscopy, and their cobalt(I) complexes were characterized. The same reduction was examined by FTIR spectroscopy for P = OEPone and OEPdione. The infrared spectra showed downshifts of the νCO band that were consistent with a cobalt(I) complex and were similar to the iron(I) complex. The two one-electron oxidations of CoII(OEPone) and CoII(OEPdione) were also carried out using visible and infrared spectroelectrochemistry. The νCO band for cobalt was less sensitive to the metal oxidation state (III vs. II) than was observed in the iron complexes. Additional upshifts in the νCO band were observed for the π-cation radical. Isotopic 18O substitution on the carbonyl group of the H2OEPone was done in order to determine the degree of mixing up the porphinone modes with the carbonyl vibrations

Poly[[μ-aqua-bis­(μ-4,4′-bipyridine-κ2 N:N′)bis­(μ-3-hy­droxy­adamantane-1-carboxyl­ato-κ2 O:O′)bis­(3-hy­droxy­adamantane-1-carboxyl­ato-κO)dicobalt(II)] hepta­hydrate]

The title coordination compound, {[Co(C11H15O3)4(C10H8N2)2(H2O)]·7H2O}n, consists of a pair of CoII atoms, four 3-hy­droxy­adamantane-1-carboxyl­ate anions (L), one water mol­ecule, two bridging 4,4′-bipyridine (4,4′-bpy) ligands and seven uncoordinated water mol­ecules. Both of the CoII ions are coordinated in a distorted octa­hedral geometry. Four L ligands bind to each pair of CoII atoms in a plane, two of which bridge the two CoII atoms as bidentate groups while the other two coordinate to a single CoII atom in a monodentate mode. Two half-mol­ecules of 4,4′-bipyridine coordinate the CoII atoms from the upside and underside. The packing features extensice O—H⋯O hydrogen bonding

ALIGNMENT DAN ANALISIS KEKERABATAN RAYAP COPTOTERMES FORMOSANUS (Isoptera: Rhinotermitidae) PADA HABITAT YANG BERBEDA DENGAN SOFTWARE BIOEDIT DAN MEGA 6 (STUDI PUSTAKA DNA SEKUENSING DARI NCBI)

Background: Bioinformatics is a science that can relate information which includes molecular biology, biochemical structure, enzymatic, cell biology, physiology and pathology by using a computerized system based on data that has been collected. Methods: sequence alignment and phylogenetic tree construction of DNA sequences registered at NCBI in the subterranean termite Coptotermes formosanus Shiraki that lives in different habitats, namely in Mississippi, Southeast Asia, and China using Bioedit and MEGA software. Results: Sequence alignment showed that termite C. formosanus isolated from MS12 gene COII (FJ870577.1) in the Mississippi area had a base pair of 790 bp, termite C. formosanus isolated from Dinghu Mountain gene COII (KU257993.1) in China has a base pair of 779 bp, and the termite C. formosanus isolated from CF003JP gene COII (EF379943.1) in Southeast Asia has a base pair of 676 bp. The construction of the phylogenetic tree shows that the termite C. formosanus isolated from Dinghu Mountain gene COII (KU257993.1) in the China region has a close kinship with the termite C. formosanus isolated from CF003JP gene COII (EF379943.1) in the Southeast Asia region, while The termite C. formosanus isolated from MS12 gene COII (FJ870577.1) in the Mississippi area is distantly related to C. formosanus (KU257993.1) from China and C. formosanus (EF379943.1) from Southeast Asia. Conclusion: Mississippi has a base pair of 790 bp, termite C. formosanus isolated from Dinghu Mountain gene COII (KU257993.1), China has a base pair of 779 bp, and termite C. formosanus isolated from CF003JP gene COII (EF379943.1), Southeast Asia has a base pair of 676 bp. China is closely related to the termite C. formosanus isolated from COII gene CF003JP (EF379943.1), Southeast Asia, while the termite C. formosanus isolated from MS12 gene COII (FJ870577.1), Mississippi is distantly related to C. formosanus (KU257993.1) from China and C. formosanus (EF379943.1) from Southeast Asia

Calculating metalation in cells reveals CobW acquires Co(II) for vitamin B12 biosynthesis while related proteins prefer Zn(II)

Protein metal-occupancy (metalation) in vivo has been elusive. To address this challenge, the available free energies of metals have recently been determined from the responses of metal sensors. Here, we use these free energy values to develop a metalation-calculator which accounts for inter-metal competition and changing metal-availabilities inside cells. We use the calculator to understand the function and mechanism of GTPase CobW, a predicted CoII-chaperone for vitamin B12. Upon binding nucleotide (GTP) and MgII, CobW assembles a high-affinity site that can obtain CoII or ZnII from the intracellular milieu. In idealised cells with sensors at the mid-points of their responses, competition within the cytosol enables CoII to outcompete ZnII for binding CobW. Thus, CoII is the cognate metal. However, after growth in different [CoII], CoII-occupancy ranges from 10 to 97% which matches CobW-dependent B12 synthesis. The calculator also reveals that related GTPases with comparable ZnII affinities to CobW, preferentially acquire ZnII due to their relatively weaker CoII affinities. The calculator is made available here for use with other proteins

Large-scale mitochondrial DNA analysis of native honey bee Apis mellifera populations reveals a new African subgroup private to the South West Indian Ocean islands

Background: The South West Indian Ocean (SWIO) archipelagos and Madagascar constitute a hotspot of biodiversity with a high rate of endemism. In this area, the endemic subspecies A. m. unicolor has been described in Madagascar. It belongs to the African lineage, one of the four described evolutionary lineages in honey bees. Despite a long beekeeping tradition and several recorded European introductions, few studies have been carried out on the diversity and proportion of honey bee subspecies. In order to identify and define which evolutionary lineages and potential sub-lineages are present in the SWIO, the COI-COII intergenic region and the ND2 gene of the mtDNA were sequenced in honey bee colonies from three archipelagos. An extensive sampling (n = 1184 colonies) was done in the Mascarene (La Réunion, Mauritius, Rodrigues), Seychelles (Mahé, Praslin, La Digue) and Comoros (Grande Comore, Mohéli, Anjouan, Mayotte) archipelagos. Islands genetic diversity was compared to newly sampled populations from Madagascar, continental African and European populations. Results: African lineage haplotypes were found in all islands (except for Rodrigues). Madagascar, Comoros and Seychelles had 100% of A lineage, 95.5% in La Réunion and 56.1% in Mauritius. Among all African colonies detected in the SWIO, 98.1% (n = 633) of COI-COII haplotypes described the presence of the subspecies A. M. unicolor. Both genetic markers revealed i) a new private AI mitochondrial group shared by the SWIO archipelagos and Madagascar distant from continental populations; ii) the private African haplotypes for each island suggested diversity radiation in the archipelagos; iii) the detection of the Comoros archipelago as a possible contact area between insular and continental African populations. The exotic European C and M lineages were only detected in the Mascarene archipelago, but striking differences of proportion were observed among islands. Merely 4.6% of European colonies were found in La Réunion whereas Mauritius cumulated 44%. Here, among the 84 observed COI-COII haplotypes, 50 were newly described including 13 which were private to the SWIO archipelagos and Madagascar. Similarly, 24 of the 34 found ND2 haplotypes were novel which included six haplotypes particular to the SWIO populations. Conclusion: A new African subgroup was described in the SWIO region with mitochondrial genetic evidence that A. m. unicolor is the indigenous subspecies of the archipelagos surrounding Madagascar. (Résumé d'auteur

Alignment of the amino terminal amino acid sequence of human cytochrome c oxidase subunits I and II with the sequence of their putative mRNAs

Thirteen of the first fifteen amino acids from the NH2-terminus of the primary sequence of human cytochrome c oxidase subunit I and eleven of the first twelve amino acids of subunit II have been identified by microsequencing procedures. These sequences have been compared with the recently determined 5'-end proximal sequences of the HeLa cell mitochondrial mRNAS and unambiguously aligned with two of them. This alignment has allowed the identification of the putative mRNA for subunit I, and has shown that the initiator codon for this subunit is only three nucleotides away from the 5'-end of its mRNA; furthermore, the results have substantiated the idea that the translation of human cytochrome c oxidase subunit II starts directly at the 5'-end of its putative mRNA, as had been previously inferred on the basis of the sequence homology of human mitochondrial DNA with the primary sequence of the bovine subunit