Photoproteins as luminescent labels in binding assays

Certain marine organisms produce calcium-activated photoproteins that allow them to emit light for a variety of purposes, such as defense, feeding, breeding, etc. Even though there are many bioluminescent organisms in nature, only a few photoproteins have been isolated and characterized. The mechanism of emission of light in the blue region is the result of an internal chemical reaction. Because there is no need for excitation through external irradiation for the emission of bioluminescence, the signal produced has virtually no background. This allows for the detection of the proteins at extremely low levels, making these photoproteins attractive labels for analytical applications. In that regard, the use of certain photoproteins, namely, aequorin, obelin, and the green fluorescent protein as labels in the design and development of binding assays for biomolecules has been reviewed. In addition, a related fluorescent photoprotein, the green fluorescent protein (GFP), has been recently employed in bioanalysis. The use of GFP in binding assays is also discussed in this review.     

Molecular orbital calculations on solvents and other small molecules: Correlation between electronic and molecular properties ν, αMOL, π*, and β.

Molecular orbital calculation by the MINDO/3 method are reported for 50 compounds used as solvents in chemical reactions. Relationships between various parameters of electronic structure and molecular properties such as dipole moment, polarizability and Taft solvent parameters are presented. Comparison between experimental values of π* and calculated values is given.     

Synthesis of mixed metal decaosmium carbido clusters: The X-ray structures of the monoanions [Os10C(CO)24Cu(NCMe)]− and [Os10C(CO)24AuPPh3]−

The high nuclearity mixed metal cluster monoanions [Os₁₀C(CO)₂₄Cu(NCMe)]^? (I) and [Os₁₀C(CO)₂₄AuPPh₃]^? (II) have been obtained by reaction of the carbido-dianion [Os₁₀C(CO)₂₄]^2? (III) with one equivalent of [Cu(NCMe)₄] [BF₄] and Ph₃PAuCl, respectively, in CH₂Cl₂. X-ray analysis of the [PPh₃Me]⁺ salts of I and II show that the Cu and Au ligands have added to capping tetrahedra of the dianion III in μ₃- and μ₂-bridging positions, respectively.     

Cobalt(II) halide complexes ofN-2-(4-picolyl)-,N-2-(6-picolyl)-andN-2-(4,6-lutidyl)-N′-phenylthioureas

Summary Co^II complexes of various stoichiometries have been isolated from reactions of the metal chlorides and bromides withN-2-(4-picolyl)-,N-2-(6-picolyl)- andN-2-(4,6-lutidyl)-N-phenylthioureas.     

A perylenedicarboxamide linker for DNA hairpins

The synthesis and properties of a perylenediamide diol linker and several DNA hairpins possessing this linker are described. The diol linker absorbs and fluoresces strongly in the visible. Hairpins having poly(dA)-poly(dT) stems have fluorescence quantum yields and decay times similar to those of the linker, indicating that hole injection does not occur from the singlet excited linker into the base pair domain. Fluorescence quenching by dG or dZ bases is observed when these bases are located near the linker. The strong distance dependence of fluorescence quenching is consistent with a superexchange mechanism for electron transfer. Failure to observe formation of the linker anion radical by means of femtosecond time resolved absorption spectroscopy is attributed to fast charge recombination. The properties and behavior of the perylene linker and its hairpins are compared to those of other arenedicarboxamide linkers.     

Transition metal ion complexes of thiosemicarbazones derived from 2-acetylpyridineN-oxide. I. The 4-methyl derivative

Summary TheN-methyl-2-[1-(2-pyridinyl-1-oxide)ethylidene]hydrazinecarbothioamide, HLO4M, has been used to prepare a series of Co^III, Ni^II and Cu^II complexes. Species with two deprotonated LO4M ligands, one LO4M and one HLO4M ligand, two HLO4M ligands and one HLO4M ligand with two small anionic ligands have been isolated. The deprotonated LO4M bonds as a tridentate ligandvia theN-oxide oxygen, the imine nitrogen (N¹ and the sulphur while the HLO4M ligand coordinates primarily as a bidentate ligandvia only the first two atoms listed above. I.r., electronic, mass and e.s.r. spectra have been used to determine the nature of these complexes. One of the more striking differences between these compounds and those prepared with other thiosemicarbazones of 2-acetylpyridine and 2-acetylpyridineN-oxide is that tetrahedral yellow [Ni(HL)X₂] rather than planar brown [NiLX] (X=Cl or Br) solids have been isolated with this ligand. Other differences in the nature of the coordination spheres of the various metal ions occur with this particular ligand when compared to previously studied thiosemicarbazone complexes.NATO Fellow, on leave from Medical Faculty, Istanbul University.     

Products from the reaction of M3(CO)12 (M = Ru or Os) with water

Reaction of the carbonyl Ru₃(CO)₁₂ with water leads to the formation of polynuclear hydrides α-H₄Ru₄(CO)₁₂, α-H₂Ru₄(CO)₁₃; the corresponding reaction with Os₃(CO)₁₂ yields the complexes (H)(OH)Os₃(CO)₁₀, H₂Os₄(CO)₁₃, H₄Os₄(CO)₁₂, H₂Os₅(CO)₁₆, H₂Os₅(CO)₁₅, H₂Os₆(CO)₁₈ and H₂Os₇(CO)₁₉C.     

Alkaloids from marine organisms. Part 8: Isolation of bisdemethylaaptamine and bisdemethylaaptamine-9-O-sulfate from an Indonesian Aaptos sp. marine sponge

Bisdemethylaaptamine (6), a proposed biosynthetic precursor of the aaptamines has been isolated from an Aaptos sp. marine sponge harvested off the Indonesian coast, and its identity confirmed by comparison of its spectral data with that of synthetic material. Bisdemethylaaptamine-9-O-sulfate (7) was also isolated from the same source. This is the first report of a sulfated aaptamine.     

Products of the reaction of H2Os3(CO)10 with cyclonona-1,2diene

Treatment of H₂Os₃(CO)₁₀ with cyclonona-l,2-diene produced HOs₃(CO)₉C₉H₁₃ and Os₂(CO)₆(C₉H₄)₂. Single crystal X ray analysis has shown that the latter is not isostructural with Fe₂(CO)₆(C₉H₁₄)₂.     

Ionic conductivity of Li2MgSn3O8 ramsdellite

The ionic conductivity of polycrystalline pellets of Li₂MgSn₃O₈ with ramsdellite-type structure was measured by complex impedance technique. The conductivity is 1.2 × 10^?8 (Ω cm)^?1 at 300°C and 2.3 × 10^?4 (Ω cm)^?1 at 450°C. The results are discussed in relation to structural properties.