Department of Biochemistry and Biophysics, University of California, Davis, California 95616.
Plant Physiol. 1973 Oct;52(4):362-7. doi: 10.1104/pp.52.4.362.
A nitrate uptake system is induced (along with nitrate reductase) when NH(4) (+)-grown Penicillium chrysogenum is incubated with inorganic nitrate in synthetic medium in the absence of NH(4) (+). Nitrate uptake and nitrate reduction are probably in steady state in fully induced mycelium, but the ratios of the two activities are not constant during the induction period. Substrate concentrations of ammonium cause a rapid decay of nitrate uptake and nitrate reductase activity. The two activities are differentially inactivated (the uptake activity being more sensitive). Glutamine and asparagine are as effective as NH(4) (+) in suppressing nitrate uptake activity. Glutamate and alanine were about half as effective as NH(4) (+). Cycloheximide interferes with the NH(4) (+)-induced decay of nitrate uptake activity. The ammonium transport system is almost maximally deinhibited (or derepressed) in nitrate-grown mycelium.
当用无机硝酸盐在合成培养基中培养 NH(4) (+) 生长的青霉素时，会诱导硝酸盐摄取系统（以及硝酸盐还原酶）。在完全诱导的菌丝体中，硝酸盐摄取和硝酸盐还原可能处于稳态，但在诱导期期间，两种活性的比例不是恒定的。铵的底物浓度会导致硝酸盐摄取和硝酸盐还原酶活性的快速衰减。这两种活性的失活程度不同（摄取活性更敏感）。谷氨酰胺和天冬酰胺与 NH(4) (+) 一样有效，可抑制硝酸盐摄取活性。谷氨酸和丙氨酸的效果约为 NH(4) (+) 的一半。环己酰亚胺会干扰 NH(4) (+) 诱导的硝酸盐摄取活性衰减。在硝酸盐生长的菌丝体中，铵转运系统几乎被最大程度地去抑制（或去阻遏）。
