Non-enzymatic glycosylation (or glycation) and inhibition of the pig heart cytosolic aspartate aminotransferase by glyceraldehyde 3-phosphate.
Glyceraldehyde 3-phosphate (Glyc3P), a glycolytic intermediate, non-enzymatically glycosylated (or glycated) and inhibited the pig heart cytoplasmic aspartate aminotransferase (cAAT). Glyc3P (5.0 mM) decreased cAAT activity by 47% after 1 min at 23 degrees C. cAAT activity remained unchanged after a 24h incubation with either glucose 6-phosphate (5.0 mM) or ribose 5-phosphate (5.0 mM). Increasing the incubation pH from 6.4 to 7.8 or the incubation temperature from 23 degrees C to 50 degrees C enhanced Glyc3P's inhibitory effect on cAAT activity. Glyc3P (250-500 microM) decreased the thermal stability of cAAT as evidenced by lowering the Tm or temperature that caused a 50% irreversible loss of cAAT activity (69 degrees C, control; 58.5 degrees C, 500 microM Glyc3P). Glyc3P decreased cAAT amino group content and increased glycation products, which were measured by adduct formation, fluorescence and protein crosslinking.
Fitzgerald
C
C
Department of Biochemistry, University of Health Sciences, Kansas City, MO 64106-1453, USA.
Swearengin
T A
TA
Yeargans
G
G
McWhorter
D
D
Cucchetti
B
B
Seidler
N W
NW
D000818:Animals; D001219:Aspartate Aminotransferases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D005986:Glyceraldehyde 3-Phosphate / Q000378:metabolism* / Q000494:pharmacology*; D006031:Glycosylation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology*; D013050:Spectrometry, Fluorescence; D013552:Swine; D013816:Thermodynamics
D005986:Glyceraldehyde 3-Phosphate; D001219:Aspartate Aminotransferases