Heme protonation affects iron-NO binding in the NO transport protein nitrophorin.

The nitrophorins (NPs) comprise an unusual group of heme proteins with stable ferric heme iron nitric oxide (Fe-NO) complexes. They are found in the salivary glands of the blood-sucking kissing bug Rhodnius prolixus, which uses the NPs to transport the highly reactive signaling molecule NO. Nuclear resonance vibrational spectroscopy (NRVS) of both isoform NP2 and a mutant NP2(Leu132Val) show, after addition of NO, a strong structured vibrational band at around 600 cm, which is due to modes with significant Fe-NO bending and stretching contribution.

Nuclear inelastic scattering and density functional theory studies of a one-dimensional spin crossover [Fe(1,2,4-triazole)(1,2,4-triazolato)](BF) molecular chain.

Nuclear inelastic scattering (NIS) experiments have been performed in order to study the vibrational dynamics of the low- and high-spin states of the polynuclear 1D spin crossover compound [Fe(1,2,4-triazole)(1,2,4-triazolato)](BF) (1). Density functional theory (DFT) calculations using the functional B3LYP* and the basis set CEP-31G for heptameric and nonameric models of the compound yielded the normal vibrations and electronic energies for high-spin and low-spin isomers of three models differing in the distribution of anionic trz ligands and BF anions. On the basis of the obtained energies a structural model with a centrosymmetric Fe(trzH)(trz) coordination core of the mononuclear unit of the chain is proposed.

A luminescent PtFe spin crossover complex.

A heterotrinuclear [PtFe] spin crossover (SCO) complex was developed and synthesized employing a ditopic bridging bpp-alkynyl ligand L and alkynyl coordinated Pt terpy units: [Fe(L-Pt)](BF) (1). We identified two different types of crystals of 1 which differ in their molecular packing and the number of co-crystallized solvent molecules: 1H (1·3.5CHCl in P1[combining macron]) and 1L (1·10CHCl in C2/c); while 1L shows a reversible SCO with a transition temperature of 268 K, the analogous compound 1H does not show any SCO and remains blocked in the HS state.

Divergent Coordination Chemistry: Parallel Synthesis of [2×2] Iron(II) Grid-Complex Tauto-Conformers.

The coordination of iron(II) ions by a homoditopic ligand L with two tridentate chelates leads to the tautomerism-driven emergence of complexity, with isomeric tetramers and trimers as the coordination products. The structures of the two dominant [Fe(II) 4 L4 ](8+) complexes were determined by X-ray diffraction, and the distinctness of the products was confirmed by ion-mobility mass spectrometry. Moreover, these two isomers display contrasting magnetic properties (Fe(II) spin crossover vs.

Isoprenoid Biosynthesis in Pathogenic Bacteria: Nuclear Resonance Vibrational Spectroscopy Provides Insight into the Unusual [4Fe-4S] Cluster of the E. coli LytB/IspH Protein.

The LytB/IspH protein catalyzes the last step of the methylerythritol phosphate (MEP) pathway which is used for the biosynthesis of essential terpenoids in most pathogenic bacteria. Therefore, the MEP pathway is a target for the development of new antimicrobial agents as it is essential for microorganisms, yet absent in humans. Substrate-free LytB has a special [4Fe-4S](2+) cluster with a yet unsolved structure.