Breiman A, Barash I
J Bacteriol. 1976 Sep;127(3):1127-35. doi: 10.1128/jb.127.3.1127-1135.1976.
L-Asparagine uptake by Stemphylium botryosum is mediated by two distinct energy- and temperature-dependent transport systems. One permease is relatively specific for L-asparagine and L-glutamine and is present in nutrient-sufficient mycelium. The specific permease shows an optimum pH at 5.2, saturation kinetics (Km = 4.4 x 10(-4) M, Vmax = 1.1 mumol/g per min), competitive gradient of L-asparagine, and higher affinity towards the L-isomer of asparagine. Amide derivatives of L-asparagine (5-diazo-4-oxo-L-norvaline or L-aspartyl hydroxamate) are the most effective competitors, alpha-amino derivative (N-acetyl asparagine) is a moderate competitor, and alpha-carboxyl derivative (L-asparagine-t-butylester) shows only slight inhibition of the specific permease. Derivatives of L-glutamine are significantly less effective competitors than those of L-asparatine. The level of the specific permease is affected by nitrogen sources and increases approximately threefold upon starvation. The nonspecific permease possesses an optimum pH at 6.8, saturation kinetics (Km = 7 x 10(-5) M, Vmax = 5 mumol/g per min, Kt = 7.4 x 10(-5) M for L-leucine), and high affinity towards various types of amino acids.
葡萄茎点霉对L-天冬酰胺的摄取由两个不同的、依赖能量和温度的转运系统介导。一种通透酶对L-天冬酰胺和L-谷氨酰胺具有相对特异性，存在于营养充足的菌丝体中。该特异性通透酶的最适pH为5.2，具有饱和动力学（Km = 4.4×10⁻⁴ M，Vmax = 1.1 μmol/g每分钟），L-天冬酰胺具有竞争梯度，且对天冬酰胺的L-异构体具有更高亲和力。L-天冬酰胺的酰胺衍生物（5-重氮-4-氧代-L-正缬氨酸或L-天冬氨酰异羟肟酸）是最有效的竞争者，α-氨基衍生物（N-乙酰天冬酰胺）是中等竞争者，而α-羧基衍生物（L-天冬酰胺叔丁酯）对特异性通透酶仅表现出轻微抑制。L-谷氨酰胺的衍生物作为竞争者的效果明显低于L-天冬氨酸的衍生物。特异性通透酶的水平受氮源影响，饥饿时会增加约三倍。非特异性通透酶的最适pH为6.8，具有饱和动力学（Km = 7×10⁻⁵ M，Vmax = 5 μmol/g每分钟，对L-亮氨酸的Kt = 7.4×10⁻⁵ M），且对各种类型的氨基酸具有高亲和力。
