Hi,

It depends on what proteins you are trying to extract.

For total cell protein extraction sonication may be better but for membrane proteins homogenization works fine.

I have used constant cell disruptor such as French press and sonicator for protein purification. French press is useful to lysis bacteria at high cell density and in large volumes. So it may useful to purify membrane proteins in large scale by using convensional protein purification methods (such as gel filtration, ion chromatograhy etc). In contract, sonication can be used to lyse bacteria in 1ml to 500ml volume. If you want to affinity purify protein in a small scale first and then want to scale up the process, then I would recommend sonication for lysing bacteria.

Both will do the job for you, for larger volume I would go for French press system.

Hope this helps 

I recommend sonication, but it depends on the what protein you are extracting!

We deal with membrane proteins. @Jaya Pratap

High pressure homogenization is okay if you have 

otherwise while using sonication protect the denaturation of enzyme by heat produced by sonicator. keep the sample carefully in ice filled box and prevent the enzyme from excessive heating.

High pressure homogenizer works better....

Thanks

Best homogenization system I have used, for bacteria or mammalian cells is the Stansted Pump (a French press system. See http://www.frenchpressurecell.com). It is scalable. Benchtop sonication is not scalable. Even small changes in volume, vessel, transducer etc. will give you different results. Also, cavitation effects of sonication can cause significant protein denaturation. Stansted Pump is scalable from 1 ml batch to 1000 litre/h continuous (on their line of instruments). If you are buying, and have a serious need for scalability, consider this. If you are on a limited budget, or have limited access to equipment, success is going to depend more on your skill in process development than on the choice of disruption equipment.

i have experienced cleavage of my protein after sonication

So better to use high pressure homogenization. It gives the best results.

Best luck

Dear Vedita,

might be a bit too late but first of all:

I would suggest to use E.coli BL21 or similar for protein expression and DH5alpha for plasmid production.

Second:

In my hands, sonication works okay (but not perfect). However, if you have access to a microfluidizer system, definetley use that instead of sionication, because there is three advantages:

1) better and more complete cell disruption , means higher output (~90%)

2) more gentle cell disruption, e.g. less heat produced = better for intact protein recovery

3) less time consuming, less noise :)

Hope that helps.