Double‐quantum <sup>1</sup>H NMR studies of nitrogen metabolism in yeast

Juretschke, Hans Paul

doi:10.1016/0014-5793(84)81254-5

Cited by 11 publications

(1 citation statement)

References 7 publications

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“…This method is applicable only to 15N with a directly bonded proton, and requires that the rate of exchange of the proton with water protons is slow relative to the'5N-'H coupling constant. For detection of [y-15N]glutamine [41], this technique may permit an enhancement in sensitivity of the order of 102-103-fold.…”

Section: Renal Metabolism Of Ammonia and Alaninementioning

confidence: 99%

A 15N-n.m.r. study of cerebral, hepatic and renal nitrogen metabolism in hyperammonaemic rats

Farrow

Kanamori

Ross

et al. 1990

Biochemical Journal

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1. Rats were infused with 15NH4+ or L-[15N]alanine to induce hyperammonaemia, a potential cause of hepatic encephalopathy. HClO4 extracts of freeze-clamped brain, liver and kidney were analysed by 15N-n.m.r. spectroscopy in combination with biochemical assays to investigate the effects of hyperammonaemia on tissue concentrations of ammonia, glutamine, glutamate and urea. 2. 15NH4+ infusion resulted in a 36-fold increase in the concentration of blood ammonia. Cerebral glutamine concentration increased, with 15NH4+ incorporated predominantly into the gamma-nitrogen atom of glutamine. Incorporation into glutamate was very low. Cerebral ammonia concentration increased 5-10-fold. The results suggest that the capacity of glutamine synthetase for ammonia detoxification was saturated. 3. Pretreatment with the glutamine synthetase inhibitor L-methionine DL-sulphoximine resulted in 84% inhibition of [gamma-15N]glutamine synthesis, but incorporation of 15N into other metabolites was not observed. The result suggests that no major alternative pathway for ammonia detoxification, other than glutamine synthetase, exists in rat brain. 4. In the liver 15NH4+ was incorporated into urea, glutamine, glutamate and alanine. The specific activity of 15N was higher in the gamma-nitrogen atom of glutamine than in urea. A similar pattern was observed when [15N]alanine was infused. The results are discussed in terms of the near-equilibrium states of the reactions involved in glutamate and alanine formation, heterogeneous distribution in the liver lobules of the enzymes involved in ammonia removal and their different affinities for ammonia. 5. Synthesis of glutamine, glutamate and hippurate de novo was observed in kidney. Hippurate, as well as 15NH4+, was contributed by co-extracted urine. 6. The potential utility and limitations of 15N n.m.r. for studies of mammalian metabolism in vivo are discussed.

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Section: Renal Metabolism Of Ammonia and Alaninementioning

confidence: 99%