Christensen U, Mølgaard L
Chemical Laboratory IV, University of Copenhagen, Denmark.
FEBS Lett. 1991 Jan 28;278(2):204-6. doi: 10.1016/0014-5793(91)80117-l.
Binding of 6-aminohexanoic acid to the AH-site, a weak lysine binding site in Glu-plasminogen, alters the conformation of the molecule. The kinetics of the binding and the accompanying conformational change are investigated at pH 7.8, 25 degrees C. Changes of intrinsic protein fluorescence were measured as a function of time after rapid mixing in a stopped-flow apparatus. The results reflect a two-step reaction mechanism: Rapid association of Glu-plasminogen and 6-aminohexanoic acid (K1 = 44 mM) followed by the conformational change (k2 = 69 s-1 and k-2 = 3 s-1) with an overall dissociation constant Kd = 2.0 mM. Thus the conformational change is rather fast, t12 = 0.01 s. Its importance for the rates of Glu-plasminogen activation reactions is discussed.
6-氨基己酸与Glu-纤溶酶原中一个较弱的赖氨酸结合位点AH位点的结合，会改变分子的构象。在pH 7.8、25℃条件下研究了这种结合及其伴随的构象变化的动力学。在停流装置中快速混合后，测量内在蛋白质荧光随时间的变化。结果反映了一个两步反应机制：Glu-纤溶酶原与6-氨基己酸快速缔合（K1 = 44 mM），随后发生构象变化（k2 = 69 s-1和k-2 = 3 s-1），总解离常数Kd = 2.0 mM。因此构象变化相当快，t1/2 = 0.01 s。讨论了其对Glu-纤溶酶原激活反应速率的重要性。
