The first restriction endonuclease that recognised a specific 6-base sequence and cut DNA was

1. Your syllabus notes that two enzymes were isolated in 1963 in E. coli that restricted phage growth. 2. One added methyl groups; the other cut DNA (a "restriction endonuclease"). 3. The first restriction endonuclease with a sequence-specific cutting site was Hind II, characterised five years later. 4. Hind II recognises a specific sequence of six base pairs. _Source: syllabus Biology, Ch 9 "Biotechnology: Principles and Processes", §9.2.1_