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

Abstract

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.