Aminotransferase Synthesis Research Articles

MECHANISM OF HORMONAL CONTROL OF RAT LIVER TYROSINE TRANSAMINASE.

Abstract Several manifestations of adrenal control of the tyrosine-α-ketoglutarate transaminase activity of rat liver are described. Immunochemical and isotopic analysis of the mechanism of this control demonstrates that activity changes reflect changes in the rate of transaminase synthesis.

The effect of isoniazid, carbutamide, propamidine and pentamidine on the activity and synthesis of β-galactosidase, and the synthesis of transaminases in Escherichia coli, strain 15, mutant M 2

1. 1. The amount of valine/glutamic acid and aspartic acid/glutamic acid transaminases in resting cells of Escherichia coli, 15, M 2, is not affected by growing the cultures in 10 −3 M isoniazid, 10 −4 M carbutamide, 5·10 −5 M pentamidine or 10 −5 M propamidine. 2. 2. The amount of β-galactosidase formed in resting cells of E. coli, 15, M 2, is not affected when cultures are grown in 10 −3 M isoniazid, 10 −4 M carbutamide or 10 −5 M pentamidine. The amount of this enzyme formed in the logarithmic phase of growth is lower in carbutamide and pentamidine grown cells than in control cultures. 3. 3. The β-galactosidase activity of cell-free extracts of E. coli, 15, M 2, is 75% and 99% inhibited by 3.3·10 −3 M propamidine and pentamidine respectively. The inhibition is competitive. Isoniazid and carbutamide at the same concentration are without effect on the activity of β-galactosidase.