to late log phase in a fermenter containing rich medium with ampicillin 100 u03bcg ml and chloramphenicol 35 u03bcg ml the culture is then induced by the addition of iptg to a final concentration of 0 5 mm and allowed to continue growing for 2 hours the cells are then harvested by centrifugation 13 purification of the noti restriction endonuclease from neb 816 all the following procedures were performed either on ice or at 4 u00b0 c 18 grams of cells were resuspended in 70 ml of buffer a 10 mm potassium phosphate ph 6 9 0 1m nacl 0 1 mm edta 5 glycerol and broken by sonication for 1 minute at full power to an o d 260 of 0 13 the extract was centrifuged at 10 000 rpm for 30 min at 4 u00b0 c and the resulting supernatant was loaded onto a phosphocellulose column 2 5 u00d7 15 cm equilibrated with buffer a the column was washed with 60 ml buffer a and then a 900 ml linear gradient from 0 1m nacl to 1 0m nacl was applied the restriction enzyme activity eluted at 0 2 to 0 3m nacl and was pooled the p cell pool was dialyzed against buffer b 0 1m nacl 10 mm tris hcl ph 7 5 10 mm mgcl 2 5 glycerol and 0 15 naazide overnight and loaded onto a heparin sepharose column 1 5 u00d7 17 cm equilibrated.