Somerville L L, Quiocho F A
Biochim Biophys Acta. 1977 Apr 12;481(2):493-9. doi: 10.1016/0005-2744(77)90282-0.
The dye 2',4',5',7'-tetraiodofluorescein is a potent inhibitor of creatine kinase (ATP:creatine N-phosphotransferase, EC 2.7.3.2) with an apparent competitive inhibition constant with respect to MgATP2- of 2.6 - 10(-5) M. The association of the dye with the enzyme elicited a red shift in the dye's spectrum, indicative of a binding site less polar than water. The dye binds to the enzyme with an equilibrium constant of dissociation of 1.7 - 10(-5) M. MgATP or MgADP competes for the dye-binding site. Creatine binds to creatine kinase-tetraiodofluorescein complex to form a ternary complex and further causes a blue-shift in the spectrum of the bound dye. The binding of the dye to fully active creatine kinase causes conformational change that was monitored by enzyme-bound 2-mercuri-4-nitrophenol, a conformation-dependent "reporter group".
染料2',4',5',7'-四碘荧光素是肌酸激酶（ATP：肌酸N-磷酸转移酶，EC 2.7.3.2）的一种强效抑制剂，相对于MgATP2-的表观竞争抑制常数为2.6 - 10(-5) M。该染料与酶的结合导致染料光谱发生红移，表明其结合位点的极性低于水。染料与酶结合的解离平衡常数为1.7 - 10(-5) M。MgATP或MgADP竞争染料结合位点。肌酸与肌酸激酶-四碘荧光素复合物结合形成三元复合物，并进一步导致结合染料的光谱发生蓝移。染料与完全活性的肌酸激酶结合会引起构象变化，这通过酶结合的2-巯基-4-硝基苯酚进行监测，2-巯基-4-硝基苯酚是一种构象依赖性“报告基团”。
