Abnormal molecules of mitochondrial aspartate aminotransferase in the liver of vitamin B-6--deficient rats may be produced in the mitochondrial matrix.
The distribution of mitochondrial aspartate aminotransferase (AspATm) in liver cells was studied in rats fed pyridoxine-deficient and control diets. Mitochondrial aminotransferase activity was found mainly in the matrix fraction, with smaller amounts in the outer membranes, intermembrane space and cytosol. The precursor of the enzyme was detected in the liver cytosol of both vitamin B-6--deficient and control rats, and its amount was similar in the two groups. When pyridoxal phosphate was added to the assay system, the ratio of enzyme activity to antigenic activity (E/A) of mitochondrial aspartate aminotransferase in the cytosol of both vitamin B-6--deficient and control rats was about 70% of that in the matrix of control rats. On the other hand, the E/A of the matrix enzyme in deficient rats was 53% of that of controls. From these results we concluded that pyridoxal phosphate is not necessary for translocation of mitochondrial aspartate aminotransferase into mitochondrial matrix and that abnormal molecules of the enzyme may be formed in the matrix of vitamin B-6--deficient rat liver.
Okada
M
M
Department of Home Economics, Faculty of Health and Living Sciences, Naruto University of Education, Tokushima, Japan.
Uchimura
N
N
Ohe
R
R
D000818:Animals; D001219:Aspartate Aminotransferases / Q000096:biosynthesis / Q000378:metabolism*; D003600:Cytosol / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D004792:Enzyme Precursors / Q000378:metabolism; D008297:Male; D008930:Mitochondria, Liver / Q000201:enzymology*; D051381:Rats; D011919:Rats, Inbred Strains; D026681:Vitamin B 6 Deficiency / Q000201:enzymology*
D004792:Enzyme Precursors; D001219:Aspartate Aminotransferases