Spectroscopic and computational investigations of Cobalt(II) binding to the innate immune protein human calprotectin.

Human calprotectin (CP) is an innate immune protein that participates in the metal-withholding response to infection by sequestering essential metal nutrients from invading microbial pathogens. CP is comprised of S100A8 (α subunit, 10.8 kDa) and S100A9 (β subunit, 13.

Sacrificial Cobalt-Carbon Bond Homolysis in Coenzyme B as a Cofactor Conservation Strategy.

A sophisticated intracellular trafficking pathway in humans is used to tailor vitamin B into its active cofactor forms, and to deliver it to two known B-dependent enzymes. Herein, we report an unexpected strategy for cellular retention of B, an essential and reactive cofactor. If methylmalonyl-CoA mutase is unavailable to accept the coenzyme B product of adenosyltransferase, the latter catalyzes homolytic scission of the cobalt-carbon bond in an unconventional reversal of the nucleophilic displacement reaction that was used to make it.

Electronic Structure of Anilinopyridinate-Supported Ru Paddlewheel Compounds.

The electronic structures of the diruthenium compounds Ru(ap)Cl (1, ap = 2-anilinopyridinate) and Ru(ap)OTf (2) were investigated with UV-vis, resonance Raman, and magnetic circular dichroism (MCD) spectroscopies; SQUID magnetometry; and density functional theory (DFT) calculations. Both compounds have quartet spin ground states with large axial zero-field splitting of ∼60 cm that is characteristic of Ru compounds having a (π*, δ*) electron configuration and a Ru-Ru bond order of ∼2.5.

Electronic, Magnetic, and Redox Properties and O Reactivity of Iron(II) and Nickel(II) o-Semiquinonate Complexes of a Tris(thioether) Ligand: Uncovering the Intradiol Cleaving Reactivity of an Iron(II) o-Semiquinonate Complex.

The iron(II) semiquinonate character within the iron(III) catecholate species has been proposed by numerous studies to account for the O reactivity of intradiol catechol dioxygenases, but a well-characterized iron(II) semiquinonate species that exhibits intradiol cleaving reactivity has not yet been reported. In this study, a detailed electronic structure description of the first iron(II) o-semiquinonate complex, [PhTt]Fe(phenSQ) [PhTt = phenyltris(tert-butylthiomethyl)borate; phenSQ = 9,10-phenanthrenesemiquinonate; Wang et al. Chem.

Dependence of surface-enhanced infrared absorption (SEIRA) enhancement and spectral quality on the choice of underlying substrate: a closer look at silver (Ag) films prepared by physical vapor deposition (PVD).

Silver (Ag) films of varying thickness were simultaneously deposited using physical vapor deposition (PVD) onto six infrared (IR) substrates (BaF(2), CaF(2), Ge, AMTIR, KRS-5, and ZnSe) in order to correlate the morphology of the deposited film with optimal SEIRA response and spectral band symmetry and quality. Significant differences were observed in the surface morphology of the deposited silver films, the degree of enhancement provided, and the spectral appearance of para-nitrobenzoic acid (PNBA) cast films for each silver-coated substrate. These differences were attributed to each substrate's chemical properties, which dictate the morphology of the Ag film and ultimately determine the spectral appearance of the adsorbed analyte and the magnitude of SEIRA enhancement.