Preparation of mare's colostrum and milk sample for 2-DE separation without acetone precipitation

Before electrophoretic separation is performed, the samples must be dissolved in a lysis buffer (necessary to keep proteins dissolved and unbound during proteomic analyses during for a separation of proteins on polyacrylamide gels). The first step in preparing samples for proteomic analyses is their precipitation using e.g. acetone. The aim of precipitation is to obtain proteins from the sample and to remove the compounds interfering with 2-D electrophoresis. Due to difficulties in dissolving some colostrum and mare's milk samples in buffer lysis electrophoretic separation of this biological material was performed without acetone precipitation of proteins. To assess the effectiveness of the applied method, after two-dimensional separation of proteins (2-DE), the obtained gels were stained and archived. The preparation of mare's colostrum and milk samples for proteomic analyses, consisting of defatting, then precipitation of caseins and separation 2-DE, which was not preceded by precipitation of the samples with acetone, resulted in the loss of many protein spots which made it impossible to identify them later using the mass spectrometer.