Do enzymes pure against Blue/White Cloning assay also pass the LO test?
NO! Blue/White Cloning assay involves digestion and re-ligation of a vector with a unique restriction enzyme sites within a lacZ alfa gene. Induction of functional beta-galactosidase by IPTG is monitored on X-Gal containing plates by percentage of white vs. blue colonies formed. The passing cut-off point is usually between 2-5% white colonies. Our studies have shown that restriction enzymes with as few as 0.16% white colonies have failed the more sensitive LO test.
