ABSTRACT
Site-specific endonuclease NspLKI has been isolated and purified to functionally pure state from soil bacterium Nocardia species LK by successive chromatography on columns with phosphocellulose, HTP hydroxyapatite, and heparin-Sepharose. The isolated enzyme recognizes the 5'-GG downward arrowCC-3' sequence on DNA and cleaves it as indicated by the arrow, i.e., it is an isoschizomer of HaeIII. The final enzyme yield is 1.105 units per gram of wet biomass. The enzyme is active in the temperature range of 25-60 degrees C with an optimum at 48-55 degrees C; it does not lose activity on storage for three days at room temperature. An optimal buffer is HRB containing 10 mM Tris-HCl, pH 7.4, 200 microgram/ml albumin, 10 mM MgCl2, and 100 mM NaCl.
Subject(s)
Deoxyribonucleases, Type II Site-Specific/metabolism , Chromatography, Ion Exchange , DNA/metabolism , Electrophoresis, Agar Gel , Enzyme Stability , Hydrogen-Ion Concentration , Substrate Specificity , TemperatureABSTRACT
Two site-specific endonucleases, RspLKI and RspLKII, have been isolated and purified to functional homogeneity from the soil bacterium Rhodococcus species LK2. RspLKI recognizes the 5'-GCATG decreases C-3' DNA sequence and RspLKII recognizes the 5'-G decreases GATCC-3' sequence (arrows indicate DNA cleavage sites). The isolated enzymes are class II site specific endonucleases and are isoschizomers of endonucleases SphI and BamHI, respectively.
Subject(s)
Deoxyribonuclease BamHI/isolation & purification , Deoxyribonucleases, Type II Site-Specific/isolation & purification , Rhodococcus equi/enzymology , Chromatography, Ion Exchange , DNA/metabolism , Deoxyribonuclease BamHI/metabolism , Deoxyribonucleases, Type II Site-Specific/metabolism , Electrophoresis, Agar Gel , Substrate SpecificityABSTRACT
The site-specific endonuclease AbaI was isolated and purified to functional purity from the soil nitrogen-fixing bacterium Azospirillum brasilense UQ 1796. Purification included successive chromatography on columns with phosphocellulose, heparin-Sepharose, and hydroxyapatite. The purified enzyme recognizes the palindromic DNA sequence 5'-T decreases ATCA-3' and cleaves it as shown by the arrow. The isolated enzyme belongs to class II restriction endonuclease and is an isoschizomer of endonuclease BclI. The enzyme of AbaI is active at 26-56 degrees C. The optimal temperature is 48 degrees C and the optimal buffer is LRB.
