Li X, Pan X M
National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, PR China.
FEBS Lett. 2000 Sep 1;480(2-3):235-8. doi: 10.1016/s0014-5793(00)01947-5.
There are two forms of rabbit muscle adenylate kinase (AK) with different 8-anilino-1-naphthalenesulfonic acid (ANS) binding properties in equilibrium solution. One form (about 70%, denoted N1) binds rapidly with ANS, whereas the other (about 30%, denoted N2) does not. Furthermore, native forms of AK should adopt different conformations for binding with substrates and products, which should be pre-existing for performing its catalytic function. The present experiments demonstrate both forms of AK distinguished by ANS probe are active. The activity of N2 is about 0.8 fold higher than N1 and shows higher susceptibility to proteolysis by trypsin. This means that the native state of AK might be an ensemble of kinetically attainable conformers and the energy landscapes of AK folding should be rugged with more than one local minimum.
在平衡溶液中，兔肌肉腺苷酸激酶（AK）有两种形式，它们具有不同的8-苯胺基-1-萘磺酸（ANS）结合特性。一种形式（约70%，记为N1）能快速与ANS结合，而另一种（约30%，记为N2）则不能。此外，AK的天然形式在与底物和产物结合时应采用不同的构象，这些构象应为执行其催化功能而预先存在。目前的实验表明，通过ANS探针区分的两种形式的AK都是有活性的。N2的活性比N1高约0.8倍，并且对胰蛋白酶的蛋白水解作用更敏感。这意味着AK的天然状态可能是一组动力学上可达到的构象异构体，并且AK折叠的能量景观应该是崎岖不平的，有不止一个局部最小值。
