Jd. Cremin et Se. Fleming, GLYCOLYSIS IS A SOURCE OF PYRUVATE FOR TRANSAMINATION OF GLUTAMINE AMINO NITROGEN IN JEJUNAL EPITHELIAL-CELLS, American journal of physiology: Gastrointestinal and liver physiology, 35(3), 1997, pp. 575-588
Previous research has shown that glucose increases transamination of g
lutamine amino nitrogen with pyruvate. It is unclear whether glucose o
r glutamine provides the pyruvate used for transamination. In the curr
ent study, it was hypothesized that glucose provides pyruvate for tran
samination of glutamine amino nitrogen. This hypothesis was tested by
tracing the metabolism of [2-C-13]glucose in these cells incubated in
the presence of [2-C-13]glucose or [2-C-13]glucose and glutamine using
C-13 nuclear magnetic resonance. Glutamine supplementation increased
alanine production but did not affect lactate production. The 1-C-13,
2-C-13, 3-C-13, 1,2-C-13, and 2,3-C-13 isotopomers of alanine and lact
ate were produced when glutamine was supplemented. Glutamine supplemen
tation increased production of 2-C-13, 1,2-C-13, and 2,3-C-13 isotopom
ers of alanine but did not affect the production of isotopomers of lac
tate. The ratio of production of [2-C-13] alanine to [3-C-13] alanine
was 37:1 when glutamine was present. The predominance of production of
[2-C-13]alanine vs. all other isotopomers demonstrates that a large p
roportion of the pyruvate used for transamination of glutamine amino n
itrogen was derived from glycolysis.