同裂酶（英语：Isoschizomers）是指识别相同的识别串行，切割产生相同的粘性末端的限制酶。比如， SphI (CGTAC/G) 和 BbuI (CGTAC/G) 是一对同裂酶。通常同裂酶中第一个被发现的酶的名字会成为这个识别位点的名称。同裂酶通常来自不同的细菌系，因此需要不同的缓冲液体系。

识别相同的识别串行，但切割位点不同的限制酶称为异裂酶。比如 SmaI (CCC/GGG) 和 XmaI (C/CCGGG) 识别一样的串行，但切割位点相差两个碱基，互为异裂酶。

识别不同的识别串行，但产生相同的粘性末端的限制酶称为同尾酶。

Isoschizomers are pairs of restriction enzymes specific to the same recognition sequence. For example, SphI (CGTAC/G) and BbuI (CGTAC/G) are isoschizomers of each other. The first enzyme discovered which recognizes a given sequence is known as the prototype; all subsequently identified enzymes that recognize that sequence are isoschizomers. Isoschizomers are isolated from different strains of bacteria and therefore may require different reaction conditions.