2-Aminoadipate-2-oxoglutarate aminotransferase isoenzymes in human liver: a plausible physiological role in lysine and tryptophan metabolism.
Two major 2-aminoadipate aminotransferase (AadAT) activities of human liver extract were separated by DEAE-Sepharose column chromatography. The faster eluting enzyme was designated AadAT-I and the other one AadAT-II. AadAT-I had a hgih Km value for aminoadipate, 20 mmol/l, and a low Km value for glutamate, 1.4 mmol/l. In contrast, AadAT-II had a low Km value for aminoadipate, 0.25 mmol/l, and a high Km value for glutamate, 12.5 mmol/l. AadAT-I and AadAT-II were mainly localized in the supernatant and mitochondrial fraction, respectively. AadAT-I demonstrated only glutamate-2-oxoadipate or 2-aminoadipate-2-oxoglutarate aminotransferase activities. AadAT-II further showed the activity of tryptophan and kynurenine. On the basis of Km values and subcellular localization of the isoenzymes, a plausible role was suggested for them involving the metabolism of lysine and tryptophan.
Okuno
E
E
Department of Biochemistry, Wakayama Medical College, Japan.
Tsujimoto
M
M
Nakamura
M
M
Kido
R
R
D051307:2-Aminoadipate Transaminase; D015153:Blotting, Western; D002845:Chromatography; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D017886:Durapatite; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007527:Isoenzymes / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008239:Lysine / Q000378:metabolism*; D000637:Transaminases / Q000302:isolation & purification / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism*
D007527:Isoenzymes; D014364:Tryptophan; D017886:Durapatite; D000637:Transaminases; D051307:2-Aminoadipate Transaminase; D008239:Lysine