An E, G and S subtype restriction enzyme that recognizes the (non-palindromic) double-stranded sequence 5'-CTGAAG-3' and cleaves respectively 22 bases after C-1 and 14 bases before C'-1; cleavage of lambda DNA is never complete. Also acts as a methylase that causes specific methylation on A-5 in 5'-CTGAAG-3', the other strand is methylated by the M.Eco57I methylase. Endonucleolytic cleavage of DNA to give specific double-stranded fragments with terminal 5'-phosphates. a 2'-deoxyadenosine in DNA + S-adenosyl-L-methionine = an N(6)-methyl-2'-deoxyadenosine in DNA + H(+) + S-adenosyl-L-homocysteine Mg(2+) is absolutely required for DNA restriction. Optimum pH is 9.0 for DNA restriction and 7.5 for methylation. Monomer. In the C-terminal section; belongs to the N(4)/N(6)-methyltransferase family.