Ohnishi M, Kawagishi T, Abe T, Hiromi K
J Biochem. 1980 Jan;87(1):273-9. doi: 10.1093/oxfordjournals.jbchem.a132734.
The aim of this work was to study the selective modification of tryptophan residues with NBS. To accomplish this, a specific method to determine tryptophan was required initially. NBS reacts with both tryptophan and tyrosine residues, which are found in most enzyme proteins, and static spectrophotometric observation, which is usually employed to follow the progress of modification, is not selective for tryptophan. However, discrimination of tryptophan from tyrosine was achieved by the kinetic method with a stoppeed-flow apparatus. The rate of modification of tryptophan residues is 10(3) times larger than that of tyrosine, so rapid stopping of the reaction of NBS brings about the selective modification of tryptophan residues. Using fluorescence-spectrophotometric and kinetic methods, the modification with NBS of model compounds of the tryptophan residue could be simply followed as a single phase, even though the reaction is complex when followed by the static spectrophotometric method.
这项工作的目的是研究用N - 溴代琥珀酰亚胺（NBS）对色氨酸残基进行选择性修饰。为实现这一目的，最初需要一种测定色氨酸的特定方法。NBS能与大多数酶蛋白中存在的色氨酸和酪氨酸残基发生反应，而通常用于跟踪修饰过程的静态分光光度观察法对色氨酸没有选择性。然而，通过使用停流装置的动力学方法实现了色氨酸与酪氨酸的区分。色氨酸残基的修饰速率比酪氨酸的修饰速率大10³倍，因此快速终止NBS反应可实现色氨酸残基的选择性修饰。使用荧光分光光度法和动力学方法，即使采用静态分光光度法跟踪反应时该反应很复杂，但色氨酸残基模型化合物与NBS的修饰过程仍可简单地作为一个单相进行跟踪。
