Nucleases of the S1/P1 family have important applications in biotechnology and molecular biology. We have performed structural analyses of SmNuc1 nuclease from Stenotrophomonas maltophilia, including RNA cleavage product binding and mutagenesis in a newly discovered flexible Arg74-motif, involved in substrate binding and product release and likely contributing to the high catalytic rate. The Arg74Gln mutation shifts substrate preference towards RNA. Purine nucleotide binding differs compared to pyrimidines, confirming the plasticity of the active site. The enzyme-product interactions indicate a gradual, stepwise product release. The activity of SmNuc1 towards c-di-GMP in crystal resulted in a distinguished complex with the emerging product 5'-GMP. This enzyme from an opportunistic pathogen relies on specific architecture enabling high performance under broad conditions, attractive for biotechnologies.

• Klíčová slova
• Stenotrophomonas maltophilia, RNA, S1/P1 nuclease, X‐ray crystallography, c‐di‐GMP cleavage,
• MeSH
• bakteriální proteiny metabolismus   chemie   genetika   MeSH
• guanosinmonofosfát cyklický metabolismus   analogy a deriváty   chemie   MeSH
• katalytická doména * MeSH
• krystalografie rentgenová MeSH
• molekulární modely MeSH
• RNA metabolismus   chemie   genetika   MeSH
• Stenotrophomonas maltophilia * enzymologie   genetika   metabolismus   MeSH
• substrátová specifita MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny MeSH
• guanosinmonofosfát cyklický MeSH
• RNA MeSH

In nature, proteins have evolved sophisticated cavities tailored for capturing target guests selectively among competitors of similar size, shape, and charge. The fundamental principles guiding the molecular recognition, such as self-assembly and complementarity, have inspired the development of biomimetic receptors. In the current work, we report a self-assembled triple anion helicate (host 2) featuring a cavity resembling that of the choline-binding protein ChoX, as revealed by crystal and density functional theory (DFT)-optimized structures, which binds choline in a unique dual-site-binding mode. This similarity in structure leads to a similarly high selectivity of host 2 for choline over its derivatives, as demonstrated by the NMR and fluorescence competition experiments. Furthermore, host 2 is able to act as a fluorescence displacement sensor for discriminating choline, acetylcholine, L-carnitine, and glycine betaine effectively.The choline-binding protein ChoX exhibits a synergistic dual-site binding mode that allows it to discriminate choline over structural analogues. Here, the authors design a biomimetic triple anion helicate receptor whose selectivity for choline arises from a similar binding mechanism.

• MeSH
• acetylcholin chemie   metabolismus   MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• cholin chemie   metabolismus   MeSH
• fosfáty chemie   metabolismus   MeSH
• kinetika MeSH
• kompetitivní vazba MeSH
• krystalografie rentgenová MeSH
• membránové transportní proteiny chemie   metabolismus   MeSH
• molekulární modely MeSH
• proteinové domény * MeSH
• protonová magnetická rezonanční spektroskopie MeSH
• Sinorhizobium meliloti metabolismus   MeSH
• transportní proteiny chemie   metabolismus   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• acetylcholin MeSH
• bakteriální proteiny MeSH
• cholin MeSH
• choline transporter MeSH Prohlížeč
• fosfáty MeSH
• membránové transportní proteiny MeSH
• transportní proteiny MeSH

Crystal structures and magnetic properties of polymeric and trinuclear heterobimetallic MnIII···PtII···MnIII coordination compounds, prepared from the Ba[Pt(CN)₄] and [Mn(L4A/B)(Cl)] (1a/b) precursor complexes, are reported. The polymeric complex [{Mn(L4A)}₂{μ⁴-Pt(CN)₄}]n (2a), where H₂L4A = N,N'-ethylene-bis(salicylideneiminate), comprises the {Mn(L4A)} moieties covalently connected through the [Pt(CN)₄]2- bridges, thus forming a square-grid polymeric structure with the hexacoordinate MnIII atoms. The trinuclear complex [{Mn(L4B)}₂{μ-Pt(CN)₄}] (2b), where H₂L4B = N,N'-benzene-bis(4-aminodiethylene-salicylideneiminate), consists of two [{Mn(L4B)} moieties, involving pentacoordinate MnIII atoms, bridged through the tetracyanidoplatinate (II) bridges to which they are coordinated in a trans fashion. Both complexes possess uniaxial type of magnetic anisotropy, with D (the axial parameter of zero-field splitting) = -3.7(1) in 2a and -2.2(1) cm-1 in 2b. Furthermore, the parameters of magnetic anisotropy 2a and 2b were also thoroughly studied by theoretical complete active space self-consistent field (CASSCF) methods, which revealed that the former is much more sensitive to the ligand field strength of the axial ligands.

• Klíčová slova
• crystal structures, magnetic anisotropy, manganese(III), platinum(II), zero-field splitting,
• MeSH
• komplexní sloučeniny chemie   MeSH
• krystalografie rentgenová MeSH
• ligandy MeSH
• magnetismus MeSH
• mangan chemie   MeSH
• molekulární struktura MeSH
• Schiffovy báze chemie   MeSH
• sloučeniny platiny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• komplexní sloučeniny MeSH
• ligandy MeSH
• mangan MeSH
• Schiffovy báze MeSH
• sloučeniny platiny MeSH

BACKGROUND: Recent efforts in the field of mesoscale effects on the structure and properties of thin polymer films call to revival interest in conformational structure and defects of a polymer backbone which has a crucial influence on electronic properties of the material. Oligo[methyl(phenyl)silylene]s (OMPSi) as exemplary molecules were studied theoretically by DFT in the form of optimal decamers and conformationally disrupted decamers (with a kink). RESULTS: We proved that transoid backbone conformation is true energy minimum and that a kink in the backbone causes significant hypsochromic shift of the absorption maximum (λ max ), while backbone conformation altering from all-eclipsed to all-anti affects λ max in the opposite way. π-π stacking was investigated qualitatively through optimal geometry of OMPSi and mutual position of their phenyls along the backbone and also quantitatively by an evaluation of molecular energies obtained from single point calculations with functionals, which treat the dispersion effect in the varying range of interaction. CONCLUSIONS: The kink was identified as a realistic element of the conformational structure that could be able to create a bend in a real aryl substituted polysilylene chain because it is stabilized by attractive π-π interactions between phenyl side groups.Graphical abstract.

• Klíčová slova
• Density functional calculations, Kink, Methyl(phenyl)silylene, Stacking interaction, UV/Vis spectroscopy,
• Publikační typ
• časopisecké články MeSH

The pi-pi interactions between benzene and the aromatic nitrogen heterocycles pyridine, pyrimidine, 1,3,5-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, and 1,2,3,4,5-pentazine are systematically investigated. The T-shaped structures of all complexes studied exhibit a contraction of the C--H bond accompanied by a rather large blue shift (40-52 cm(-1)) of its stretching frequency, and they are almost isoenergetic with the corresponding displaced-parallel structures at reliable levels of theory. With increasing number of nitrogen atoms in the heterocycle, the geometries, frequencies, energies, percentage of s character at C, and the electron density in the C--H sigma antibonding orbital of the complexes all increase or decrease systematically. Decomposition analysis of the total binding energy showed that for all the complexes, the dispersion energy is the dominant attractive contribution, and a rather large attraction originating from electrostatic contribution is compensated by its exchange counterpart.

• MeSH
• benzen chemie   MeSH
• chemické modely * MeSH
• dusík chemie   MeSH
• elektrony MeSH
• heterocyklické sloučeniny chemie   MeSH
• molekulární modely MeSH
• přenos energie MeSH
• stereoizomerie MeSH
• vodíková vazba MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• benzen MeSH
• dusík MeSH
• heterocyklické sloučeniny MeSH