Multisite-binding turn-on fluorescent probe for monitoring mitochondrial ATP levels fluctuation in live cells

10.1002/anie.201510003Angewandte Chemie International Edition5551773-177

A self-assembled luminescent host that selectively senses ATP in water.

Metal-ion-directed self-assembly has been used to construct kinetically inert, water-soluble heterometallic Ru2Re2 hosts that are potential sensors for bioanions. A previously reported metallomacrocycle and a new derivative synthesised by this approach are found to be general sensors for bioanions in water, showing an “off–on” luminescent change that is selective for nucleotides over uncharged nucleobases. Through a change in the ancillary ligands coordinated to the ruthenium centres of the host, an “off–on” sensor has been produced. Whilst this host only shows a modest enhancement in binding affinities for nucleotides relative to the other two host systems, its sensing response is much more specific. Although a distinctive “off–on” luminescence response is observed for the addition of adenosine triphosphosphate (ATP), related structures such as adenine and guanosine triphosphate (GTP) do not induce any emission change in the host. Detailed and demanding DFT studies on the ATP- and GTP-bound host–guest complexes reveal subtle differences in their geometries that modulate the stacking interactions between the nucleotide guests and the ancillary ligands of the host. It is suggested that this change in stacking geometries affects solvent accessibility to the binding pocket of the host and thus leads to observed difference in the host luminescence response to the guests

Multivalent helix mimetics for PPI-inhibition.

The exploitation of multivalent ligands for the inhibition of protein-protein interactions has not yet been explored as a supramolecular design strategy. This is despite the fact that protein-protein interactions typically occur within the context of multi-protein complexes and frequently exploit avidity effects or co-operative binding interactions to achieve high affinity interactions. In this paper we describe preliminary studies on the use of a multivalent N-alkylated aromatic oligoamide helix mimetic for inhibition of p53/hDM2 and establish that protein dimerisation is promoted, rather than enhanced binding resulting from a higher effective concentration of the ligand. This journal i

Optimized reaction pair of the CysHis tag and Ni(II)-NTA probe for highly selective chemical labeling of membrane proteins

Chemical labeling of proteins with synthetic molecular probes offers the possibility to probe the functions of proteins of interest in living cells. However, the methods for covalently labeling targeted proteins using complementary peptide tag-probe pairs are still limited, irrespective of the versatility of such pairs in biological research. Herein, we report the new CysHis tag-Ni(II) probe pair for the specific covalent labeling of proteins. A broad-range evaluation of the reactivity profiles of the probe and the CysHis peptide tag afforded a tag-probe pair with an optimized and high labeling selectivity and reactivity. In particular, the labeling specificity of this pair was notably improved compared to the previously reported one. This pair was successfully utilized for the fluorescence imaging of membrane proteins on the surfaces of living cells, demonstrating its potential utility in biological research

[Benzyl(2-pyridylmeth­yl)amine]dichloridomercury(II)

The Hg atom in the title compound, [HgCl2(C13H14N2)], adopts a distorted tetra­hedral geometry, being ligated by two N atoms of the benzyl(2-pyridylmeth­yl)amine (bpma) ligand and two Cl atoms. The dihedral angle between the least-squares planes through the chelate ring and Cl—Hg—Cl atoms is 85.4 (1)°. The phenyl ring on the bpma ligand is twisted out of the pyridine plane, forming a dihedral angle of 76.0 (3)°. Disorder in this ring is also noted with two coplanar conformations having equal site occupancies

Electron microscopic detection of single membrane proteins by a specific chemical labeling

Electron microscopy (EM) is a technology that enables visualization of single proteins at a nanometer resolution. However, current protein analysis by EM mainly relies on immunolabeling with gold-particle-conjugated antibodies, which is compromised by large size of antibody, precluding precise detection of protein location in biological samples. Here, we develop a specific chemical labeling method for EM detection of proteins at single-molecular level. Rational design of α-helical peptide tag and probe structure provided a complementary reaction pair that enabled specific cysteine conjugation of the tag. The developed chemical labeling with gold-nanoparticle-conjugated probe showed significantly higher labeling efficiency and detectability of high-density clusters of tag-fused G protein-coupled receptors in freeze-fracture replicas compared with immunogold labeling. Furthermore, in ultrathin sections, the spatial resolution of the chemical labeling was significantly higher than that of antibody-mediated labeling. These results demonstrate substantial advantages of the chemical labeling approach for single protein visualization by EM

[Bis(2-pyridylmeth­yl)amine]dichloridomercury(II)

The Hg atom in the title complex, [HgCl2(C12H13N3)], adopts a square-pyramidal geometry, being ligated by three N atoms of the tridentate bis­(2-pyridylmeth­yl)amine ligand and two Cl atoms, with one of the latter occupying the apical position. Disorder is noted in the amine portion of the ligand and this was modelled over two sites, with the major component having a site-occupancy factor of 0.794 (14)

9-Chloro-2,4-dimethoxy­acridinium trifluoro­methane­sulfonate

In the mol­ecular structure of the title compound, C15H13ClNO2 +·CF3SO3 −, the meth­oxy groups are nearly coplanar with the acridine ring system, making dihedral angles of 0.4 (2) and 5.1 (2)°. Multidirectional π–π contacts between acridine units are observed in the crystal structure. N—H⋯O and C—H⋯O hydrogen bonds link cations and anions, forming a layer structure

Di-μ-chlorido-bis­{[2-({[2-(2-pyrid­yl)eth­yl](2-pyridylmeth­yl)amino}meth­yl)phenol]zinc(II)} bis­(perchlorate) dihydrate

The title compound, [Zn2Cl2(C20H21N3O)2](ClO4)2·2H2O, consists of a dinuclear ZnII cationic complex, two disordered perchlorate anions and two water mol­ecules as solvate. The [Zn2(μ-Cl)2(HL)2]2+ cation [HL is 2-({[2-(2-pyrid­yl)eth­yl](2-pyridylmeth­yl)amino}meth­yl)phenol] has a centrosymmetric structure with the ZnII ions in a distorted octa­hedral environment surrounded by an N3OCl2 donor set. HL acts as a tetra­dentate ligand through three N atoms from one amine group and two pyridyl arms and one O atom from the phenolic arm. The three N-donor sites of the HL ligand are arranged in meridional fashion, with the pyridine rings coordinated in trans positions with respect to each other. Consequently, the amine and phenol groups are trans to the asymmetric di-μ-chlorido exogenous bridges. A polymeric chain is formed along [010] by C(12)R 4 2(8) inter­molecular hydrogen bonding. The perchlorate anion is disordered and was modelled by two sites in a 0.345 (18):0.655 (18) ratio. Water–perchlorate O—H⋯O inter­actions form cyclic structures, while phenol–water O—H⋯O inter­actions generate an infinite chain. In addition, weak inter­molecular C—H⋯π(Ph) inter­actions between pyridine donor and phenol acceptor groups of neighboring cations build a two-dimensional polymeric structure parallel to (110)