DNA cleavage activity of wt R.Eco29kI and its mutants. (a) Electrophoresis of the reaction products of phage φ80vir DNA with R.Eco29kI and mutant proteins in 0.8% agarose. (b) Electrophoresis of the cleavage products of the 200 bp DNA fragment by R.Eco29kI and mutant proteins in 5 % polyacrylamide gel under non-denaturing conditions. (c) Electrophoresis of the reaction products of the 200 bp DNA fragment with R.Eco29kI and mutant proteins in 8% polyacrylamide gel under denaturing conditions. Gel patterns with cleavage products are shown at the points after which the reaction rate ceased to rise. s – substrate, 200 bp DNA fragment with Eco29kI site; p – products, the cleavage products of 200 bp DNA fragment after treatment by R.Eco29kI.