Protocol

Precipitation of Proteins by Organic Solvents

This protocol was adapted from "Concentrating Solutions of Protein," in Appendix 3 of Purifying Proteins for Proteomics (ed. Simpson). Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY, USA, 2004.

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INTRODUCTION

Most proteins larger than 20 kDa precipitate from aqueous solution when the concentration of organic solvent reaches ~50%. Typically, larger proteins and more hydrophilic proteins precipitate at lower organic solvent concentrations than do smaller hydrophobic proteins. Addition of organic solvents can therefore be used as a simple method of concentrating proteins from large volumes or as a way to simultaneously concentrate and fractionate proteins. In the latter case, trial solvent fractionation experiments should be conducted.

MATERIALS

Reagents

Ethanol or acetone chilled to -20ºC

If 96% grade ethanol is used, the volume of ethanol required to achieve the . . . [Full Text of this Article]

METHOD