RESTRICTING ENDONUCLEASES FROM SHIGELLA-SONNEI-47

Abstract

Two restriction endonucleases SsoI and SsoII, belonging to restriction enzymes class II, were isolated from S. sonnei. The structure of the site sensitive to SsoI and SsoII was studied after fragmentation of testor DNA and direct determination of nucleotide sequence. SsoI is an isoshysomere of the EcoRI restriction endonuclease from Escherichia coli. Restriction endonuclase SsoII proved to be a new enzyme, which hydrolyzed the sequence 5'' ...CCNGG.. 3'' and was distinct from known restriction endonuclease as shown by studies of the type of DNA hydrolyzed. A 3-step procedure is developed for isolation of SsoII restriction endonuclease involving the consecutive chromatography on blue Sepharose, phosphocellulose PII and phenyl-Sepharose. Restriction endonuclease SsoI and EcoRI were isolated by means of isoelectrofocusing using ampholines.