Why most commercial protease inhibitor cocktails do not contain EDTA? - (Aug/11/2009 )

Hi,

I'm new to protein work. I'm just curious why most of the commercial complete protease inhibitors do not contain EDTA, since it is used as a protease inhibitor and need to be added to the lysis buffer.

Thanks!

It may well make the cocktail unstable in some manner, probably by chelating out metal ions.

It depends on your downstream application. In some applications, having a divalent ion chelator (EDTA and EGTA) will interfere. These include metal chelating affinity chromatography and 2D electrophoesis.

Also, some proteins require divalent cations for their stability.

Hey,

I agree with miBunny. It depends upon yr application, there are both kinds of inhibitors available-with and without EDTA.

Best,
TC

eilosei on Aug 12 2009, 04:51 AM said:

Thank you!

Some enzymes require metal ions for structural or catalytic function. EDTA can strip out these metals or bind to them, making the enzyme useless.

So what is the benefit of adding EDTA? Or rather, what are the drawbacks of EDTA-free protease inhibitor? Why would you get protease inhibitor with EDTA if you can just add it yourself? Is it less expensive?

The benefit is that EDTA will inhibit many proteases by chelating the essential metal ions in them, therby preventing the protease from working. Getting a protease with EDTA ensures that the amount of EDTA you get each time is the same and has been treated in the same manner (i.e. not left on someone's bench for several years etc.) I don't know about price, but I think it is cheaper to get EDTA containing ones IIRC.