Restriction endonuclease EcoRI and similar proteins
Restriction endonuclease EcoRI (EC 184.108.40.206), also termed R.EcoRI, or endonuclease EcoRI, is a type II restriction enzyme that require only divalent metals (such as Mg2+ or Mn2+) as cofactors to catalyze the hydrolysis of DNA. EcoRI recognizes the double-stranded sequence GAATTC and cleaves after G-1. The family also includes an EcoRI isoschizomer, RsrI endonuclease, which also catalyzes the cleavage of duplex DNA and oligodeoxyribonucleotides between the first two residues of the sequence GAATTC. RsrI differs from EcoRI in its N-terminal amino acid sequence, susceptibility to inhibition by antibodies, sensitivity to N-ethylmaleimide, isoelectric point, state of aggregation at high concentrations, temperature lability, and conditions for optimal reaction. It displays a reduction of specificity ("star activity") under conditions that also relax the specificity of EcoRI.