Detritiation of L-[3-3H]alanine in the glutamate-pyruvate transaminase reaction.
The detritiation of L-[3-3H]alanine in the reaction catalyzed by pig heart glutamate-pyruvate transaminase was monitored in the absence or presence of lactate dehydrogenase. The results indicated that each monodirectional conversion of L-[3-3H]alanine to [3-3H]pyruvate resulted in the generation of 3HOH at a rate representing one-third of the total 3H flux. No isotopic discrimination in reaction velocity between tritiated and 14C-labelled L-alanine was observed. The mathematical modelling of the reaction revealed that, as a consequence of the detritiation process, the steady-state ratio in L-[3-3H]alanine/[3-3H]pyruvate does not inform on either the absolute or relative size of the amino acid and 2-keto acid pools.
Manuel y Keenoy
B
B
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Bodur
H
H
Malaisse
W J
WJ
D000409:Alanine / Q000378:metabolism*; D000410:Alanine Transaminase / Q000378:metabolism*; D000818:Animals; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008962:Models, Theoretical; D009206:Myocardium / Q000201:enzymology; D013552:Swine; D014316:Tritium / Q000378:metabolism*
D014316:Tritium; D007770:L-Lactate Dehydrogenase; D000410:Alanine Transaminase; D000409:Alanine