Rapid desalting and protein recovery with phenol after ammonium sulfate fractionation

Abstract Ammonium sulfate (AS) fractionation is often used in protein and enzyme purification; however, the resultant protein pellets have a high salt content and desalting by dialysis is required prior to next analysis. Here, we have developed a phenol‐based method for quick desalting and concentrating proteins after AS fractionation of complex olive leaf protein extract. After redissolving, AS precipitates were desalted with phenol extraction and the abundance of β‐glucosidase in each fraction was monitored with a specific antibody. The results of electrophoresis and Western blot showed the feasibility of the method. The method is quick and universal, and does not need much technique. Ammonium sulfate (AS) is the most common salt used to fractionate complex protein samples by step‐wise precipitation [1]. AS fractionation provides crude purification of proteins away from nonproteins and it is typically included in protein purification protocols. However, protein precipitates obtained from AS fractionation have a high salt content, and need to be desalted prior to the next analysis. One way to remove excess AS is by dialyzing protein samples against a buffer low in salt content. This works fine though time consuming. Additionally, after dialysis, it is often needed to concentrate dilute protein solutions because the analysis requires small volumes, such as in gel electrophoresis. Recent research in plant proteomics calls for a rapid method for desalting and protein recovery after AS fractionation.