Using unopened restriction enzyme "expired" in 2010/11 - (Jun/14/2012 )

The many unused 'gems' we find in our lab from previous post-docs/students.

Would a restriction enzyme stored untouched at -20C be viable even after it's use-by-date?
Anyone who has used it before and seen that it stills cut perfectly?

I've used several REs that have been well past their use by dates, with no problem.

You could just give it a go and see?

It's common for labs in a research environment to use RE's that are years past their use-by-dates.
As long as the enzymes have been stored in consistent standard conditions they're almost always fine.
I'd suggest running a little test of them - if they work, they work. If in doubt throw them out.

If, however, you work in a regulated (that is, accredited) laboratory you'll have to look at if you can use these enzymes according to your system.
Speak to your supervisor.

I have used old enzymes many times. If they have been stored in proper conditions, you should not worry. I have used enzymes from 1998 and they worked perfectly well!