Building a Better Buffer

Every molecular biologist knows about Tris, but few have questioned its suitability as an electrophoretic buffer component. An intrepid pair of researchers at Johns Hopkins' Sidney Kimmel Comprehensive Cancer Center have studied Tris and found it to be lacking.¹

No paper has ever claimed that Tris was the best buffer, says Scott Kern, professor of oncology and pathology. "It's just something that somebody once used, then somebody else used it, and pretty soon you had a herd mentality." Tris buffers actually hamper DNA electrophoresis through their high conductivity. The heat and current generated during an electrophoresis run can melt and distort the gel.

Seeking a better formula, Kern and postdoc Jonathan Brody tested a variety of sodium salts at different concentrations. The winner: sodium borate (SB), whose good conductivity and resolution allow gels to run five times faster than Tris-buffered gels. It is also less expensive. Kern estimates that...