Chemical binding

About: Chemical binding is a research topic. Over the lifetime, 1822 publications have been published within this topic receiving 52516 citations.

A highly active, robust photocatalyst heterogenized in discrete cages of metal–organic polyhedra for CO2 reduction

Abstract: The heterogenization of photocatalytic molecules typically enhances stability at the expense of activity. Therefore, a new approach to stabilizing molecular catalysts without compromising their original catalytic features is highly desired. In this study, we found that Zr-based metal–organic polyhedra (MOP) stabilized the photocatalytic compound ReTC [ReI(CO)3(BPYDC)(Cl), BPYDC = 2,2′-bipyridine-5,5′-dicarboxylate] without degrading its catalytic activity. ReTC was chemically bound to discrete cages of the MOP and was found to maintain its maximum CO2-to-CO conversion activity (660 h−1 turnover frequency (TOF)) for at least 24 h under visible light irradiation. The free molecular form of the same compound (H2ReTC) initially showed an activity of 131 h−1 TOF, which was lost within 2 h. The cumulative turnover number of ReTC-MOP after a 24 h reaction was 12 847, which was 42.0 times the value of 306 for molecular ReTC. The high catalytic activity and stability of ReTC-MOP are attributed to the fact that this MOP material provides an extremely small framework for chemical binding of ReTC, such that the catalyst has a high degree of motional freedom and enhanced light absorption while being protected in the reaction solution.

Structure of Daunomycin; X-ray Analysis of N-Br-Acetyl-Daunomycin Solvate

Abstract: THE antibiotic daunomycin was discovered and studied by Di Marco and co-workers1–5 who found it to have cytotoxic and antimitotic activity. Extensive chemical work by Arca-mone and co-workers6–9 has established the total absolute configuration as in Fig. 1, which gives the formula of the N-Br-acetyl derivative. Daunomycin interferes with nucleic acid metabolism in both mammalian10 and bacterial11 cells and the formation of a complex between daunomycin and nucleic acids has been studied12–16. The nature of the chemical binding between antibiotics which affect ribonucleic acid synthesis and DNA has been discussed16 and it has been suggested that the amino as well as either quinone17,18 or hydroxyl groups of the chromophore are responsible for hydrogen bonding to the DNA helix. An understanding of this effect is important as the binding of daunomycin to DNA is most likely responsible for the biological activity of this antibiotic. To determine the detailed stereochemical features of daunomycin, the relative orientation of the sugar ring to the aglycone moiety and the nature of the hydrogen bonding in the solid state, we began X-ray crystallographic studies.

Stabilization of proteins and peptides by chemical binding with chondroitin

Abstract: Peptides, polypeptides, proteins, proteinaceous hormones, and enzymes are modified by covalently bonding chondroitin thereto, whereby their stability toward in vivo degradation is increased.

Detection of Escherichia coli O157:H7 using immunosensor based on surface plasmon resonance

Abstract: An immunosensor based on surface plasmon resonance (SPR) with a self-assembled protein G layer was developed for the detection of Escherichia coli O157:H7. A self-assembled protein G layer on a gold (Au) surface was fabricated by adsorbing the mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol at various molar ratios and by activating chemical binding between free amine (-NH 2 ) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) in series. The formation of a self-assembled protein G layer on an Au substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The surface morphology analyses of the self-assembled protein G layer on the Au substrate, monoclonal antibody (Mab) against E. coli O157:H7 which was immobilized on protein G, and bound E. coli O157:H7 extracts on immobilized Mab against E. coli O157:H7 were performed by atomic force microscopy (AFM). The detection limit of the SPR-based immunosensor for E. coli O157:H7 was found to be about 10 4 cells/ml.