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The synthesis and anion binding properties of B[F.sub.2] complexes of [beta]-tetraethyl-substituted Ketonesare described with and without electron-withdrawing ethoxycarbonyl moieties at pyrrole [alpha]-positions. The substituents at pyrrole rings of these acyclic anion receptors have played a main role in controlling not only the polarization of binding sites (NH and CH) but also the relative stabilities of the preorganized conformations and the degrees of sterical repulsion.

Research has been conducted on the dioxygen-binding non-heme diiron protein hemerythrin. The preparation of the dinucleating bis(carboxylate) ligand dibenzofuran-4,6-bis(diphenylacetate) as a synthetic model for the dioxygen-binding non-heme diiron protein hemerythrin is discussed.

Research has been conducted on the (mu-oxo)bis(mu-carboxylato)diiron(III) complex. The substitution of two methanol ligands by a bidentate hfac (super)- anion is described.

A family of peroxo-bridged diiron (II) complexes was synthesized which matched exactly the combination of carboxylate and imidazole donors of the Hperoxo intermediate in the catalytic cycle of soluble methane monooxygenase. X-ray crystallographic methods were used to investigate and clarify their structures. These studies furnish the most accurate compositional models of the Hperoxo intermediate reported to date and are discussed.

A study on the possibility that the psg gene in Rhodospirillum rubrum contains a 3,4-desaturase and that its disruption produces nonnatural carotenoids is presented. The Rhodospirillum ST4 mutant with a single Tn5 lesion has been isolated wherein a latent branching of the biosynthetic pathway has been discovered. The unnatural carotenoids may have been produced by the incorporation of a cryptic branch in the linear pathway for spirilloxanthin biosynthesis. Results show that the ST4 mutant is a good system for studying the role of carotenoids in bacterial photosynthesis.

The bis(pseudohalide) complexes (Fe2O(mu-XDK)(bpy)2(NCS)2) (1), (Fe2O(mu-XDK)(bpy)2(NCSe)2) (2) and (Fe2O(mu-XDK)(bpy)2(N3)2) (3) (XDK = the dianion of m-xylylenediamine bis(Kemp's triacid imide), bpy = 2,2'-bipyridyl) were synthesized. They were investigated by X-ray crystallography and UV-vis, IR, resonance Raman and Mossbauer spectroscopy. Compounds 1 and 3 were observed to model structural and spectroscopic characteristics of the isothiocyanate- and azide-bound derivatives of methemerythrin, respectively.

Experimental study enables the assignment of hyperfine-shifted signals of the paramagnetic 1H NMR spectra of Co(II)-substituted Cys112 Asp azurin from Pseudomonas aeruginosa for all the coordinated groups. Spectral studies show little or no localization of unpaired spin density on Met 121 protons of the Cys112 Asp protein. The interpretation of electronic absorption and NMR data is confirmed by a computerized model that visualizes Asp112 and His117 in the ligation sphere and the presence of Gly45 carbonyl and His46.

Circular dichroism spectra of the self-assembled porphyrins which showed intense Cotton effects are mirror-images for the two 31-enantiomers and proved that the supramolecular chirality is dependent on the configuration at the 31-stereocenter. Friedel-Crafts conditions at short reaction times with high concentrations of catalyst and at 0-4 degree [Celsius] was used to perform diacylation of copper 10, 20-bis(3,5-di-tert-butylphenylporphyrin) to obtain 3,17-diacyl-substituted porphyrins, out of the 12 possible regioisomers.

A simple synthetic route for converting chlorophyll(Chl)-a to bacteriochlorophyll(Bchl)-c is described. Separation of methyl bacteriopheophorbide (MBPhe)-c, transesterification of the 17-propionate group and magnesium insertion successfully led to naturally occurring BChl-c.

The study presents a complete characterization of the resultant chromosomes that are formed by the isotopic replacement of their pigments and lipid from Chlorobium limicola. The analysis shows that the reassembled chlorosomes have similar and longer morphological structures and are found in the same excited-state dynamics in the pigment assembly.

How the bacteriochlorophyll (BChl) c molecules are assembled in the aggregate of an isomeric mixture from Chlorobium limicola in the solid state, as determined by intermolecular [sup.13.C]-[sup.13.C] dipolar correlations, and how the assembly of BChl c in a large aggregate in the solid state compares to, or contrasts to, those in the smaller aggregates in suspension are considered. Results reveal that the structure of the solid-state aggregate of BChl c contains both types of stackings, the dimer-based stacking and the (pseudo) monomer-based stacking.

A study was conducted to characterize synthetic frameworks of the deoxy and oxy forms of the non-heme dioxygen-binding protein hemerythrin by synthesizing an asymmetric (mu-hydroxo)bis(mu-carboxylato)diiron(II) complex. Results indicated that the dinucleating dicarboxylate ligand supports the preparation and synthesis of new iron complexes with structural and spectroscopic properties of deoxy- and oxyHR.

Analysis of the electronic absorption spectrum of gold(I)-substituted wild-type Pseudomonas aeruginosa apoprotein (azurin) reveals a Au(I)-centered 5d to 6p transition in the trigonal Au(I)N2S (N2 = His46, His117; S = Cys112) complex. The complex is considerably distorted as evident from the wide emission band. The blue shift band for the Au(I) Met121Gly protein corresponds to an axial interaction in the binding-site cavity. With the reduction in the excited state distortion, the emission band is narrowed.

The gene named bciD, which encodes the enzyme involved in C7-formylation in bacteriochlorophyll e biosynthesis, was found and investigated by insertional inactivation in the brown-colored green sulfur bacterium Chlorobaculum limnaeum (previously called Chlorobium phaeobacteroides). The bciD mutant cells were green in color, and accumulated bacteriochlorophyll c homologs bearing the 7-methyl group, compared to C7-formylated BChl e homologs in the wild type. BChl-c homolog compositions in the mutant were further different from those in Chlorobaculum tepidum which originally produced BChl c: (31S)-8-isobutyl-12-ethyl-BChl c was unusually predominant. [ABSTRACT FROM AUTHOR]

Synthesizes the neutral (...-oxo)bis(...-carboxylato)diiron(III) complexes, where XDK is the doubly deprotonated form of m-xylylenediamine bis(Kemp's triacid imide) and bpy is 2,2'-bibyridyl. Information on XDK groups; How the synthesize was conducted; Discussions surrounding the study; Results of the study.

A mixture of bacteriochlorophyll (BChI) c isomers was extracted from the cells of Chlorobium limicola that were grown in the media of 13C-enriched and natural-abundance isotopic compositions. The magic-angle spinning 13C NMR proton-driven spin-diffusion spectra were recorded with mixing times of 50, 100, and 250 ms for two different kinds of in vitro aggregates, one consisting of pure [13C]BChI c and the other consisting of a 1:1 mixture of [`13C]BCh1 c and [12C]BChl c; those peaks whose intensities were reduced to ~¼ by this dilution were assigned to intermolecular 13C-13C dipolar correlation peaks. On the other hand, the nearest-neighbor intermolecular carbon—carbon close contacts with distances of 4-6 Å were simulated, to predict observed correlation peaks, for six different models of BChI c assembly. They include weakly overlapped monomers forming structure 1 and structure 2, strongly overlapped dimers forming straight and inclined columns, and weakly overlapped dimers forming aligned and displaced layers. Comparison between the observed correlation peaks and the predicted carbon—carbon close contacts, for both the macrocycles and the side chains, led us to a conclusion that the weakly overlapped dimers forming displaced layers are most likely the assembly of the BChl c molecules in the aggregate. [ABSTRACT FROM AUTHOR]