15N enrichment of ammonium, glutamine-amide and urea, measured via mass isotopomer analysis of hexamethylenetetramine

Dawei Yang, Michelle Puchowicz, France David, Lisa Powers, Mitchell L. Halperin, Henri Brunengraber

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Ammonium is an important intermediate of protein metabolism and is a key component of acid-base balance. Investigations of the metabolism of NH4+ in vivo using isotopic techniques are difficult because of the low concentration of NH4+ in biological fluids and because of frequent artifactual isotopic dilution of the enrichment of NH4+ during the assay. A new gas chromatographic mass spectrometric method was designed to monitor the 15N enrichment and concentration of NH4+ in vivo. These are both calculated from the mass isotopomer distribution of hexamethylenetetramine (HMT) formed by reacting NH4+ with formaldehyde. The enrichment of NH4+ is amplified four times since the HMT molecule contains four atoms of nitrogen derived from NH4+. This allows the measurement of low 15N enrichment of NH4+, down to 0.1%. 15N enrichment of urea and of the amide N of L-glutamine are measured by enzymatic release of NH4+ and conversion of the latter to HMT. These new techniques facilitate in vivo investigations of the metabolism of NH4+ and related compounds.

Original languageEnglish (US)
Pages (from-to)1130-1136
Number of pages7
JournalJournal of Mass Spectrometry
Volume34
Issue number11
DOIs
StatePublished - Jan 1 1999
Externally publishedYes

Fingerprint

Methenamine
Glutamine
Ammonium Compounds
Metabolism
Amides
Urea
Formaldehyde
Dilution
Assays
Nitrogen
Gases
Atoms
Molecules
Fluids
Proteins

All Science Journal Classification (ASJC) codes

  • Spectroscopy

Cite this

15N enrichment of ammonium, glutamine-amide and urea, measured via mass isotopomer analysis of hexamethylenetetramine. / Yang, Dawei; Puchowicz, Michelle; David, France; Powers, Lisa; Halperin, Mitchell L.; Brunengraber, Henri.

In: Journal of Mass Spectrometry, Vol. 34, No. 11, 01.01.1999, p. 1130-1136.

Research output: Contribution to journalArticle

Yang, Dawei ; Puchowicz, Michelle ; David, France ; Powers, Lisa ; Halperin, Mitchell L. ; Brunengraber, Henri. / 15N enrichment of ammonium, glutamine-amide and urea, measured via mass isotopomer analysis of hexamethylenetetramine. In: Journal of Mass Spectrometry. 1999 ; Vol. 34, No. 11. pp. 1130-1136.
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