What is the best way/kit to extract total proteins from biopsy tissue?

Question

I need to extract total protein from 2mm skin biopsies for western blots.

I was thinking about miRNeasy Micro Kit (50) Cat. #217084 while it's ok for total RNA extraction, I am not sure if it is still fine for proteins. There's a trizol (quiazol) step that provides you with organic fraction that suppose to contain protein fraction, but I am still not sure if it's a best way.

There's also a so-called Urea Sample Buffer (USB), that contains urea, 20% SDS, glycerol, Tris and Pyronin Y - but I am not sure it's a good choice since the percentage of SDS is high and it will be a disaster if I will try to disrupt my tissue.

Or, maybe there's a better solution or kit for that purpose?

Answer 1

This entirely depends on what you want to get out of it. If you need the RNA or DNA, then trizol extraction can work, but no need to buy a special kit for it, just the trizol and chloroform will work too - though for miRNA (as opposed to mRNA), a kit is a good way to go.

If you just want the protein, use a dedicated protein lysis solution for this. Something like RIPA buffer is a good start. make sure you add protease inhibitors and work with cold solutions to prevent proteolysis of the proteins. Depending on what you want to find, you may need to disrupt the biopsies a bit first - chop them into smaller chunks and/or do a collagenase digestion to allow removal of the mass proteins and look at less abundant ones. RIPA buffer is quite strong, so you may want to use a gentler solution without the SDS and/or deoxycholate, but this (again) depends on your final aims.