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This paper provides a comprehensive overview of metabolites, including lipids and lipid-like compounds, nitrogen metabolites, oligopeptides and amino acid derivatives, produced by cyanobacteria of the genera Anabaenopsis, Aphanizomenon, Aulosira, Cylindrospermopsis, Cylindrospermum, Nodularia, and Richelia of the family Nostocaceae.
We tested the relationship between Sphagnum growth and the amount of nitrogen stored in free amino acids in a fertilisation experiment with intact peat monoliths in an open greenhouse in The Netherlands. Three nitrogen deposition scenarios were used: no nitrogen deposition, field conditions and a doubling of the latter, corresponding to 0, 40 and 80 kg N ha(-1 )year(-1). Growth of Sphagnum as expressed by height increment was reduced in the 80 kg N treatment, but showed no correlation with the total nitrogen tissue concentration or with the concentration of individual or pooled free amino acids. The amount of nitrogen stored in free amino acids increased concomitantly with deposition, although it lagged more and more behind the total nitrogen concentration, the latter pointing to the accumulation of unmeasured nitrogen compounds. Asparagine clearly acted as the major storage compound for nitrogen in Sphagnum stem tissue, whereas arginine fulfilled this function to a lesser extent in the capitulum. It appears that nitrogen-induced growth inhibition of Sphagnum is related to acclimation rather than to certain threshold concentrations of amino nitrogen or total nitrogen. We propose that when Sphagnum is exposed to a step increase of nitrogen, its nitrogen metabolism does not adapt fast enough to keep up with the enhanced uptake rate. This imbalance between nitrogen uptake and assimilation may lead to an accumulation of toxic NH(4)(+ )in the cell and a subsequent reduction in growth.
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A novel nitrogen-containing compound, named xylactam (1), was isolated from the fruiting bodies of ascomycete Xylaria euglossa together with two known compounds penochalasin B2 and neoechinulin A. Their structures were elucidated on the basis of spectral data.
Shaw, Paul D. (University of Illinois, Urbana), and Nancy Wang. Biosynthesis of nitro compounds. I. Nitrogen and carbon requirements for the biosynthesis of beta-nitropropionic acid by Penicillium atrovenetum. J. Bacteriol. 88:1629-1635. 1964.-beta-Nitropropionic acid was produced by Penicillium atrovenetum when this fungus was grown on a Raulin-Thom medium in shake flasks. The nitro compound was formed in the early stages of growth, and the total amount in the medium decreased when the fungus reached the end of the log phase. When increasing amounts of nitrate were substituted for the ammonia in the growth medium, production of beta-nitropropionic acid decreased. Aspartic acid did not promote the synthesis of the nitro compound unless either ammonium chloride or sodium tartrate was also added to the medium. The addition of small amounts of hydroxylamine or sodium nitrite to the Raulin-Thom medium stimulated beta-nitropropionic acid production to a greater degree on a molar basis than the amount of hydroxylamine or nitrite added. The nature of possible precursors to the nitro group of beta-nitropropionic acid is discussed.
In the United States Pharmacopeia (USP), 0.1 N perchloric acid in acetic acid volumetric solution (hereafter HClO4 VS) used for non-aqueous titration has specified a water content between 0.02 and 0.05%. Preparing this titrant with such a narrow range of water content is very time consuming, precludes the use of commercially available titrants, and, consequently, prompted an investigation to try and expand the range up to 0.5%. In this study, the titrimetric results obtained using HClO4 VS containing more water were very close to those obtained using the USP specified titrants. A maximum assay difference of 0.7% in the titrations of three selected nitrogen-containing compounds, clonidine hydrochloride, dipyridamole, and adenosine were observed. The titrimetric results obtained using these titrants were also precise with RSDs of not more than 0.4%. Therefore, a wider range of water content in HClO4 VS between 0.02 and 0.5% is suggested for the USP potentiometric titration of nitrogen-containing compounds.
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Bacteria which utilized nitroaromatic compounds (0.5 mM) as sole source of nitrogen were isolated from soil. With 2,6-dinitrophenol and succinate as carbon source, a Pseudomonas strain was isolated which liberated and assimilated nitrite. Approximately 2 mol of NO(2) per mol of 2,6-dinitrophenol was released by resting cells. The xenobiotic compound was totally degraded, although specific growth yields were low even with succinate as a carbon source.
The effects of a novel kind of nitrogen heterocycle compound, which was synthesized in our laboratory previously, on human chronic myelogenous leukemia K562 cells were investigated. The morphological changes were observed by Acridine orange (AO) staining. The screened results through DNA fragmentation and the Annexin V-FITC/PI staining assay showed that compound 8 blocked cell cycles at G(1) phase which led to apoptosis. The increase of caspase-3, 8, and 9 was detected, indicating that both of death-receptor and mitochondria-pathways were activated. Compound 8 induced a biphasic alteration in mitochondrial membrane potential of K562 cells. A dramatic elevation of Ca(2+) was also observed. In addition, a transient increase of ROS was also involved in the process. This study showed that compound 8 might be a potential chemopreventive agent for chronic myelogenous leukemia. It would guide our future work to synthesize more compounds derived from compound 8, which might have better effect, and to determine the target protein. Moreover, it might also provide a background mechanism for the introduction of this new type of promising therapeutic agent.
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The use of N-acylhydrazones as electrophiles in reactions with nucleophiles has recently made some important advances. N-Acylhydrazones, which can be readily prepared and stored, act as stable imine surrogates in these reactions. The hydrazide products are useful, often chiral building blocks which can be transformed into various nitrogen-containing compounds by cleavage of the N--N bond. The N-acyl groups often play important roles as templates for metal catalysis in controlling stereochemistry. This Minireview summarizes the most recent results of N-acylhydrazone chemistry, and provides an overview of current developments in this field.
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The dynamics of consumption of amine and ammonium nitrogen and glucose in the process of Xanthomonas rubrilineans 67 growth and biosynthesis of leucine aminopeptidase was studied. It was shown that the rate of leucine, alanine and glycine consumption as a source of amine nitrogen out of 16 amino acids was the highest during the fermentation. Addition of these three amino acids or their mixtures to the medium at definite stages of the fermentation process increased the leucine aminopeptidase biosynthesis by 50 to 100 per cent. Ammonium nitrogen was not used by X.rubrilineans 67. The consumption of glucose during the fermentation was even: by the 24th hour of the process the medium contained about 10 per cent of the glucose initial concentration. The optimal temperature for the culture growth and leucine aminopeptidase biosynthesis was determined. It was shown to be 28 degrees C. Higher aeration increased the culture productivity.
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