Restriction enzymescan be divided into 4 groups based on their recognition sequence, subunit composition, cleavage position, and cofactor requirements.

Following is a list of the four types of restriction enzymes:

Type I restriction enzymesare compromised of one enzyme with different subunits for recognition, cleavage, and methylation. This enzyme recognizes and methylates at the same sequence but cleaves DNA up to 1000 base pairs away from the initial recognition site.

Type II restriction enzymes妥协的two different enzymes, which cleave or modify the recognition sequence.

Type III restriction enzymesconsist of one enzyme with two different subunits, each for recognition and modification or cleavage. This enzyme recognizes and methylates at the same sequence but cleaves 24-26 base pairs away from the initial recognition site.

类型IIs限制性内切酶妥协的two different enzymes with asymmetrical recognition sequence. Cleavage occurs on one side of recognition site up to 20 base pairs away.