I need very pure protein for FACE analysis. As last stage I'm going to use purification from SDS-PAGE: cut out single band from the gel and then extract protein. I'm afraid that SDS (still bound to my protein of interest after extraction) will interfere with PNGase F digestion (though reaction mixture contains SDS at final concentration 0.05%). Could you, please, suggest method to remove SDS from my protein sample after extraction SDS-protein complex from gel ??? By now I have found only 1. info on GeBa kit, but it needs lots of buffer changes, 2. guanidine-HCl purification, that needs several precipitation steps and in both cases I could end up with unsufficient amount of protein.