scholarly journals Activity of the liver mitochondrial aspartate aminotransferase and malate dehydrogenase in rats with toxic hepatitis under conditions of alimentary protein deficiency

2019 ◽  
Vol 21 (3) ◽  
pp. 14-20
Author(s):  
O. M. Voloshchuk ◽  
◽  
G. P. Kopylchuk ◽  
Keyword(s):  
Malate Dehydrogenase ◽  
Aspartate Aminotransferase ◽  
Toxic Hepatitis ◽  
Protein Deficiency ◽  
Mitochondrial Aspartate Aminotransferase ◽  
Alimentary Protein Deficiency

scholarly journals Kinetic studies of the uptake of aspartate aminotransferase and malate dehydrogenase into mitochondria in vitro

1985 ◽  
Vol 228 (2) ◽  
pp. 493-503 ◽  
Author(s):  
E Marra ◽  
S Passarella ◽  
E Casamassima ◽  
E Perlino ◽  
S Doonan ◽  
...  
Keyword(s):  
Malate Dehydrogenase ◽  
Binding Sites ◽  
Aspartate Aminotransferase ◽  
Kinetic Studies ◽  
Membrane System ◽  
Model System ◽  
Kinetic Measurements ◽  
Enzymes Inhibition ◽  
Mitochondrial Aspartate Aminotransferase

Kinetic measurements of the uptake of native mitochondrial aspartate aminotransferase and malate dehydrogenase into mitochondria in vitro were carried out. The uptake of both the enzymes is essentially complete in 1 min and shows saturation characteristics. The rate of uptake of aspartate aminotransferase into mitochondria is decreased by malate dehydrogenase, and vice versa. The inhibition is exerted by isoenzyme remaining outside the mitochondria rather than by isoenzyme that has been imported. The thiol compound beta-mercaptoethanol decreases the rate of uptake of the tested enzymes; inhibition is a result of interaction of beta-mercaptoethanol with the mitochondria and not with the enzymes themselves. The rate of uptake of aspartate aminotransferase is inhibited non-competitively by malate dehydrogenase, but competitively by beta-mercaptoethanol. The rate of uptake of malate dehydrogenase is inhibited non-competitively by aspartate aminotransferase and by beta-mercaptoethanol. beta-Mercaptoethanol prevents the inhibition of the rate of uptake of malate dehydrogenase by aspartate aminotransferase. These results are interpreted in terms of a model system in which the two isoenzymes have separate but interacting binding sites within a receptor in the mitochondrial membrane system.

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