evaluation of sonication

[Duncan Clark]

Historians believe that in newspost 
<1144233782.131152.114780 at t31g2000cwb.googlegroups.com> on Wed, 5 Apr 
2006, "cheetah.zao at gmail.com" <cheetah.zao at gmail.com> penned the 
following literary masterpiece:
>Does anyone know some quick methods to check whether E.coli cells are
>oversonicated or not, since it is tricky to balance protein denaturing
>and yields?

In 28 years I've never run up against over-sonicating. Just keep 
everything on ice and by trial and error work out how long you can 
sonicate for in one burst without taking your extract above temperature 
X (where you decide what X is). Allow to cool on ice then repeat and so 
on until cells are broken.

This can take at least an hour or so of total time if you are doing 6 
bottles of 500ml extract with three to four  5minute stints of 
sonication using a 3/4 inch probe and 350W.

Duncan
-- 
I love deadlines. I especially like the whooshing noise they make as
they go flying by.

Duncan Clark
GeneSys Ltd.