A series of homometallic dinuclear lanthanide complexes containing nonequivalent metal centers [Ln(2)(LH(2))(LH)(CH(3)OH)(N(3))]·xMeOH·yH(2)O [1, Ln = Dy(III), x 0, y 2; 2, Tb(III), 1, 1] have been synthesized [LH(4) 6-((bis(2-hydroxyethyl)amino)-N’-(2-hydroxybenzylidene)picolinohydrazide] and characterized. The assembly contains two different types nine-coordinated centers, because the binding...

In the first step of olfaction, odorants are bound and solubilized by small globular odorant binding proteins (OBPs) which shuttle them to the membrane of a sensory neuron. Low ligand affinity and selectivity at this step enable the recognition of a wide range of chemicals. Honey bee Apis mellifera's OBP14 (AmelOBP14) binds different plant odorants in a largely hydrophobic cavity. In long molec...

Recent x-ray crystallographic studies of the acetylcholine-binding protein (AChBP) suggest that loop C, found at the circumference of the pentameric molecule, shows distinctive conformational changes upon antagonist and agonist occupation. We have employed hydrogen-deuterium exchange mass spectrometry to examine the influence of bound ligands on solvent exposure of AChBP. Quantitative measureme...

Nitrile hydratase (NHase) is an iron-containing metalloenzyme that converts nitriles to amides. The mechanism by which this biochemical reaction occurs is unknown. One mechanism that has been proposed involves nucleophilic attack of an Fe-bound nitrile by water (or hydroxide). Reported herein is a five-coordinate model compound ([Fe(III)(S(2)(Me2)N(3)(Et,Pr))](+)) containing Fe(III) in an envir...

A series of cadmium carboxylate compounds in a sulfur-rich environment provided by the tris(2-tert-butylmercaptoimidazolyl)hydroborato ligand, namely, [Tm(Bu(t))]CdO2CR, has been synthesized via the reactions of the cadmium methyl derivative [Tm(Bu(t))]CdMe with RCO2H. Such compounds mimic aspects of cadmium-substituted zinc enzymes and also the surface atoms of cadmium chalcogenide crystals, a...

Computational chemistry has recently introduced the improved reaction field theory and now is capable of evaluating the bulk solvent effect quite accurately. It is time to expand this capability to mixed solvents, as it is often extremely useful through is still not well understood. For example, the determination of rates of complexations of divalent metal ions with a tridentate metal-ion indic...

The gas-phase recognition of native amino acids and the conformational properties of three glucosylthioureidocalix[4]arenes () were studied theoretically and experimentally using ab initio calculations, ESI-FTICR,(1)H and (13)C NMR MS. The conformational and complexation properties of the glucocalixarenes were dependent on the number of glucose units at the upper rim and the length of the alkyl...

In the presence of Na(+) ions, two N(2)-modified guanosine derivatives, N(2)-(4-n-butylphenyl)-2',3',5'-O-triacetylguanosine (G1) and N(2)-(4-pyrenylphenyl)-2',3',5'-O-triacetylguanosine (G2), are found to self-associate into discrete octamers that contain two G-quartets and a central ion. In each octamer, all eight guanosine molecules are in a syn conformation and the two G-quartets are stacke...