There are hundreds,thousands of them known now, and each one has a specific character and one aspects of its character is that it only binds and cuts at a particular sequence of DNA.

已知的有成百上千种,每一种都有自己的特性,特性之一是,只结合和切割特定的某一种DNA序列

耶鲁公开课 - 生物医学工程探索课程节选