Phosphonomycin, a new antibiotic produced by strains of streptomyces

Phosphonomycin is a newly discovered antibiotic produced by streptomycetes. It is effective, when administered by the oral route, to mice infected with Gram-positive or Gram-negative microorganisms. The antibiotic is bactericidal and inhibits cell-wall synthesis.

The stereochemistry of nitrate esters. II. Symmetric stretching frequencies of the nitrato group in nitrate esters of l,4;3,6-di-anhydrohexitols (4,8-dihydroxy-cis-2,6-dioxabicyclo[3.3.0]octanes)

In the infrared spectra of mono- and di-nitrate esters of the l,4;3,6-dianhydrides of d-mannitol, d-glucitol, and l-iditol in benzene solution (0.04 M in nitrato groups), the frequencies of the va(NO2) and v(ON) bands (singlets) were 1 645 ± 3 and 843 ± 3 cm−1, respectively, whereas the vs(NO2) band occurred at frequencies characteristic of either an endo (1 282 ± 1 cm−1) or an exo (1 274 ± 1 cm−1) configuration of the nitrato group; the ratios of the band areas were 1.5:1.0:1.0, respectively.The stereospecific frequency of the vs(NO2) band was attributed to non-bonded intramolecular interaction between the nitrato group and vicinal oxy groups on the basis of the spectra run in a series of solvents and the molecular conformations determined by X-ray crystallography. This new stereochemical probe permitted the assignment of the structure, configuration, and conformation in a series of nitrate esters.

Thiamine-dependent accumulation of tetramethylpyrazine accompanying a mutation in the isoleucine-valine pathway

A mutant of Corynebacterium glutamicum was found to accumulate high concentrations of a material which crystallized upon cooling of the broth. The compound was identified as tetramethylpyrazine. The mutant was found to require isoleucine, valine, leucine, and pantothenate for growth. All four requirements probably result from the loss of a single enzyme of the isoleucine-valine pathway. Since similar mutants of Neurospora crassa accumulate acetoin, the present mutant probably forms tetramethylpyrazine from acetoin. Accumulation of tetramethylpyrazine was dependent upon addition of thiamine. This observation is consistent with the known activity of diphosphothiamine as a cofactor for the formation of acetolactate (a precursor of acetoin) from pyruvate.

Production of xanthosine-5'-monophosphate and inosine-5'-monophosphate by auxotrophic mutants of a coryneform bacterium

Although most microorganisms with genetic blocks in the purine nucleotide sequence excrete breakdown products, a coryneform bacterium was found to accumulate intact 5'-nucleotides in the extracellular medium. Adenineless mutants accumulated 0.4 to 0.6 g of inosine-5'-monophosphate per liter of broth. The yield of this nucleotide was increased to 0.8 to 0.9 g per liter when such mutants were mutated to xanthine dependence. Induction of a specific guanine requirement in adenineless auxotrophs resulted in cultures capable of producing high yields of xanthosine-5'-monophosphate (3 to 4 g per liter). Pure xanthosine-5'-monophosphate was isolated from broth by a procedure involving ion-exchange chromatography, charcoal adsorption, and barium precipitation.

THE STEREOCHEMISTRY OF HALOGEN DISPLACEMENT BY NITRATE ION RACEMIZATION AND RETENTION OF CONFIGURATION IN THE SYNTHESIS OF DINITRATE ESTERS

The reaction of silver nitrate in dry acetonitrile with 2,5-dideoxy-2,5-diiodo-1,4;3,6-dianhydro-L-iditol resulted in formation of the dinitrate esters of the 1,4;3,6-dianhydrides of D-mannitol, D-glucitol, and L-iditol. Similarly both endo- and exo-nitrato groups were introduced in displacement of the endo-halogen in the 2-deoxy-2-iodo-5-O-acetyl and 2-deoxy-2-iodo-5-O-p-toluenesulfonyl derivatives of 1,4;3,6-dianhydro-L-iditol. Since both types of nitrato groups were stable to silver nitrate, the racemization occurred during the displacement and was attributed to formation of cyclic carbonium ion intermediates. The steric effect of the adjacent ring in the carbonium ions apparently suppressed the termolecular, ion-pair mechanism previously established for the metathesis of acyclic alkyl halides and caused preferential formation of the exo-nitrato derivatives.The heterogeneous reaction of meso-dibromostilbene with silver nitrate in acetic acid or acetonitrile gave meso-dihydrobenzoin dinitrate with overall retention of configuration. This result could be most readily reconciled with the contrasting sequence of retention and inversion previously reported for meso- and dl-2,3-dibromobutane if participation of neighboring phenyl groups occurred in the second displacement step.

THE ACTION OF PYRIDINE ON THE DINITRATE ESTERS OF 1,4;3,6-DIANHYDROHEXITOLS

In contrast to the rapid and selective replacement of a secondary O-nitro group by hydrogen in the hexitol hexanitrates at 25–50 °C, the dinitrate esters of the 1,4;3,6-dianhydrides of D-mannitol, D-glucitol, and L-iditol (cis-isohexides) reacted slowly in anhydrous pyridine at 87–115 °C. The chief products were a polymer, nitrogen oxides, and pyridinium nitrate; the yield of mononitrates did not exceed 10% and none of the parent diols were formed.The relative rates of the first-order decomposition of the nitroxy groups in the isomeric dinitrates were in reverse order to that for SN2 reaction at carbon in these compounds. Activation energies and frequency factors were determined and water was shown to have a retarding effect.Thermal decomposition of the dinitrates in solution in nitrobenzene, m-xylene, or sym-tetrachloroethane was much slower than the pyridine reaction at the same temperature and was independent of the polarity of the solvent and the conformation of the ester.

Biochemical Studies on Sockeye Salmon During Spawning Migration: XI. The Free Histidine Content of the Tissues

During the first 250 miles (400 km) of spawning migration of Fraser River sockeye salmon (Oncorhynchus nerka) the free histidine content of the muscle, alimentary tract, and head+skin+bones+tail decreased to a small fraction of the initial value. A further decrease occurred in the levels of this amino acid in the alimentary tract during the subsequent 415-mile (657-km) migration to the spawning grounds, no change being observed with the other tissues. Comparatively small changes in free histidine were found with heart, spleen, liver, kidney and gonads during migration.

THE ACTION OF SODIUM IODIDE ON O-p-TOLUENE-SULPHONYL-1,4;3,6-DIANHYDRIDES OF D-MANNITOL, D-GLUCITOL, AND L-IDITOL

In the displacement reaction with sodium iodide in acetic anhydride solution the rates of reaction of four isohexide tosyl esters were compared to that of an O-acetyl-O-tosylisosorbide recently described. The tosyloxy group in the latter compound was replaced rapidly and was therefore in the 5-endo-position, the compound being correctly named 2-O-acetyl-5-O-p-toluenesulphonyl-1,4;3,6-dianhydro-D-glucitol. The product of the reaction was isolated as a crystalline material, and was identified as 2-O-acetyl-5-deoxy-5-iodo-1,4;3,6-dianhydro-L-iditol.

Facial Palsy

No abstract available.