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The nitrogen-fixing symbiont of alfalfa, Sinorhizobium meliloti, is able to use myo-inositol as the sole carbon source. Putative inositol catabolism genes (iolA and iolRCDEB) have been identified in the S. meliloti genome based on their similarities with the Bacillus subtilis iol genes. In this study, functional mutational analysis revealed that the iolA and iolCDEB genes are required for growth not only with the myo-isomer but also for growth with scyllo-and D-chiro-inositol as the sole carbon source. An additional, hypothetical dehydrogenase of the IdhA/MocA/GFO family encoded by the smc01163 gene was found to be essential for growth with scyllo-inositol, whereas the idhA-encoded myo-inositol dehydrogenase was responsible for the oxidation of D-chiro-inositol. The putative regulatory iolR gene, located upstream of iolCDEB, encodes a repressor of the iol genes, negatively regulating the activity of the myo-and the scyllo-inositol dehydrogenases. Mutants with insertions in the iolA, smc01163, and individual iolRCDE genes could not compete against the wild type in a nodule occupancy assay on alfalfa plants. Thus, a functional inositol catabolic pathway and its proper regulation are important nutritional or signaling factors in the S. meliloti-alfalfa symbiosis.The sugar alcohol inositol, or cyclohexanehexol, occurs in several different stereoisomers, of which the myo-form (Fig. 1, compound 1) is the most abundant (1). myo-Inositol plays important structural and signaling roles in animal and plant cells (22). In the environment, myo-inositol mainly occurs in the phosphorylated form and is involved in the phosphate cycle of terrestrial and freshwater ecosystems (41). The stereoisomers D-chiro-and scylloinositol have recently attracted attention, because they have shown therapeutic potentials for diabetes and Alzheimer's disease, respectively (11, 21). Although there is only limited knowledge about the metabolism of D-chiro-and scyllo-inositol (25, 50), the catabolism of myo-inositol has been studied in a variety of microorganisms, including some members of the Firmicutes (17, 46, 51), Enterobacteriaceae (4,19,40), and Rhizobiaceae (16,29). The myo-inositol catabolic pathway and its regulation are best understood in the Gram-positive bacterium Bacillus subtilis. The B. subtilis iol genes are organized in a divergon comprising iolABCDEFGHIJ and iolRS (47-49). In the proposed inositol catabolic pathway, the myo-inositol dehydrogenase oxidizes myoinositol to its corresponding ketone 2-keto-myo-inositol (2KMI), which is then further catabolized by the actions of IolE, -D, -B, -C, -J, and -A (Fig. 1). The inducer of the inositol catabolic pathway in B. subtilis is the product of the IolC reaction, 2-deoxy-5-keto-D-gluconic acid 6-phosphate (DKGP; compound 6 in Fig. 1), which antagonizes the binding of the IolR repressor to the iol promoter region (51).Sinorhizobium meliloti, the nitrogen-fixing symbiont of alfalfa, can use myo-inositol as the sole carbon source (15). The idhA-encoded myo-inositol dehydrogenase had been s...

We employed palladium-catalyzed coupling procedures for the synthesis of new C8-adenosine adducts of various arylamines (aniline, benzidine, 4-aminobiphenyl, and 2-aminofluorene).[reaction: see text]

Over the last three decades, the rational design of chiral ligands for asymmetric catalysis has increasingly replaced the trial‐and‐error approach. A well‐known analytical reagent, 1,10‐phenanthroline, is now being employed as a template for the development of chiral ligands. In most cases these heterocyclic ligands have been functionalized in the peripheral region utilizing three prevailing ligand templates. Chiral groups are either introduced in the 2‐, 3‐, 8‐ and/or 9‐position (I, II) or are incorporated by ring fusion to phenanthroline (III). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Since the discovery of hexacarbonylvanadium(0) and hexacarbonylvanadate(1-) by Calderazzo and co-workers in 1959 and 1960, 1,2 these substances have been key precursors to a variety of vanadium compounds, including inorganic noncarbonyl species, 3 organovanadium complexes, 4 and other vanadium carbonyls. 5 Neutral V(CO) 6 is of special interest in that it is the only isolable 17-electron homoleptic metal carbonyl and exhibits fascinating chemical properties that are often reminiscent of iodine and classic pseudohalogens. 6 Although V(CO) 6 has been obtained by the direct carbonylation of bis (naphthalene)vanadium, 7 the best preparations involve the oxidation of [V(CO) 6 ] À by anhydrous HCl 8 or 100% orthophosphoric acid. 9 The procedure presented herein is based on a prior study, 9c but has been improved by the use of an easily constructed Schlenk tube receiver that should also be useful for the isolation of other volatile, air-sensitive, and/or thermally unstable substances. Original syntheses of [V(CO) 6 ] À entailed high-pressure reductive carbonylations of VCl 3 , requiring special equipment and potentially dangerous conditions. 2,9a Later Calderazzo and Pampaloni developed a far safer atmospheric-pressure * Checkers obtained reduced yields of [V(CO) 6 ] À in the range of 40-45% when the initial steps were carried out under a nitrogen atmosphere. y Checkers found that 16-20 h was necessary for all VCl 3 to dissolve, in accord with Ref. 14. * The checkers found that filtration using a Büchner funnel with filter paper was effective and took much less time than filtering with a glass frit.