Akent'eva N P, Evstigneeva Z G, Pushkin A V, Solov'eva N A, Kretovich V L
Biokhimiia. 1983 Jul;48(7):1209-13.
In the presence of ATP and Mg2+ L-methionine sulfoximine irreversibly inhibits homogeneous glutamine synthetase (EC 6.3.1.2) from pea chloroplasts (I0.5 = 1.0 x 10(-7) M; Ki = 6.25 . 10(-8) M. Glutamate (but not NH4Cl) exerts a protective effect, which is enhanced when glutamate and NH4Cl are simultaneously present in the reaction mixture. The inhibiting action of L-methionine sulfoximine with respect to glutamate is of a mixed type. ATP and Mg-ATP produce the same non-competitive protective effect on L-methionine sulfoximine. The data obtained suggest that the formation of a quaternary complex (or a transition state) between the enzyme and all its substrates is essential for the catalysis.
在ATP和Mg2+存在的情况下，L-蛋氨酸亚砜亚胺不可逆地抑制豌豆叶绿体中的纯谷氨酰胺合成酶（EC 6.3.1.2）（I0.5 = 1.0×10−7 M；Ki = 6.25×10−8 M）。谷氨酸（但不是NH4Cl）具有保护作用，当反应混合物中同时存在谷氨酸和NH4Cl时，这种保护作用会增强。L-蛋氨酸亚砜亚胺对谷氨酸的抑制作用是混合型的。ATP和Mg-ATP对L-蛋氨酸亚砜亚胺产生相同的非竞争性保护作用。所获得的数据表明，酶与其所有底物之间形成四元复合物（或过渡态）对于催化作用至关重要。
