Thalenfeld B, Grossowicz N
J Gen Microbiol. 1976 May;94(1):131-41. doi: 10.1099/00221287-94-1-131.
A thermophilic bacillus growing on acetamide as both carbon and nitrogen sources produces an inducible amidase. This amidase hydrolysed the following amides in decreasing order or activity, in comparison with acetamide (1.00): propionamide (0.97), fluoroacetamide (0.84), formamide (0.35) and glycinamide (0.12). Cyanoacetamide, dimethylacetamide, dimethylformamide and urea also induced the synthesis of the amidase, but were not substrates of the enzyme. Studies with protoplasts suggest that the amidase is located in the cytoplasm. Glucose strongly inhibited amidase synthesis; and limiting nitrogen did not release this inhibition. Urea strongly inhibited amidase activity in a competitive manner; but the inhibition caused by iodoacetamide and cyanoacetamide was non-competitive. Both thioacetamide and thiourea were effective inhibitors of enzyme induction. Bacteria grown on a succinate-minimal medium exhibited a lag in amidase synthesis, which could be eliminated by decreasing the concentration of succinate. Acetate- or pyruvate-grown cultures behaved similarly, while those grown on alanine or glutamate exhibited no lag in enzyme induction. In the mutant strain E21, repression of amidase synthesis by glucose was much less evident and no lag for induction was apparent with any of the other carbon sources mentioned.
一种以乙酰胺作为碳源和氮源生长的嗜热芽孢杆菌可产生一种诱导型酰胺酶。与乙酰胺（活性为1.00）相比，这种酰胺酶对以下酰胺的水解活性依次降低：丙酰胺（0.97）、氟乙酰胺（0.84）、甲酰胺（0.35）和甘氨酰胺（0.12）。氰基乙酰胺、二甲基乙酰胺、二甲基甲酰胺和尿素也可诱导酰胺酶的合成，但它们不是该酶的底物。原生质体研究表明，酰胺酶位于细胞质中。葡萄糖强烈抑制酰胺酶的合成；而限制氮源并不能解除这种抑制作用。尿素以竞争性方式强烈抑制酰胺酶的活性；但碘乙酰胺和氰基乙酰胺引起的抑制作用是非竞争性的。硫代乙酰胺和硫脲都是酶诱导的有效抑制剂。在琥珀酸盐基本培养基上生长的细菌在酰胺酶合成方面表现出滞后现象，降低琥珀酸盐浓度可消除这种滞后现象。以乙酸盐或丙酮酸盐为碳源生长的培养物表现类似，而以丙氨酸或谷氨酸为碳源生长的培养物在酶诱导方面没有滞后现象。在突变菌株E21中，葡萄糖对酰胺酶合成的阻遏作用不太明显，并且使用上述任何一种其他碳源诱导时均未出现滞后现象。
