The occurrence of cell-associated enterotoxin B in Staphylococcus aureus

Sample preparation and fractionation for proteome analysis and cancer biomarker discovery by mass spectrometry

Sample preparation and fractionation technologies are one of the most crucial processes in proteomic analysis and biomarker discovery in solubilized samples. Chromatographic or electrophoretic proteomic technologies are also available for separation of cellular protein components. There are, however, considerable limitations in currently available proteomic technologies as none of them allows for the analysis of the entire proteome in a simple step because of the large number of peptides, and because of the wide concentration dynamic range of the proteome in clinical blood samples. The results of any undertaken experiment depend on the condition of the starting material. Therefore, proper experimental design and pertinent sample preparation is essential to obtain meaningful results, particularly in comparative clinical proteomics in which one is looking for minor differences between experimental (diseased) and control (nondiseased) samples. This review discusses problems associated with general and specialized strategies of sample preparation and fractionation, dealing with samples that are solution or suspension, in a frozen tissue state, or formalin-preserved tissue archival samples, and illustrates how sample processing might influence detection with mass spectrometric techniques. Strategies that dramatically improve the potential for cancer biomarker discovery in minimally invasive, blood-collected human samples are also presented.

Methods for samples preparation in proteomic research

Sample preparation is one of the most crucial processes in proteomics research. The results of the experiment depend on the condition of the starting material. Therefore, the proper experimental model and careful sample preparation is vital to obtain significant and trustworthy results, particularly in comparative proteomics, where we are usually looking for minor differences between experimental-, and control samples. In this review we discuss problems associated with general strategies of samples preparation, and experimental demands for these processes.

Purification and partial characterization of a putative precursor to staphylococcal enterotoxin B

A putative precursor to staphylococcal enterotoxin B (SEB) has been identified as a component of purified membranes from Staphylococcus aureus S6. Agarose gel immunodiffusion analysis of the solubilized membranes demonstrated an immunoreactive protein that formed complete lines of identity with purified extracellular SEB. This putative precursor (pSEB) also had a different electrophoretic mobility from that of extracellular SEB when analyzed by immunoelectrophoresis. When membrane proteins from S6 were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then transferred to nitrocellulose sheets and probed with I-125 labeled, affinity-purified anti-SEB, the pSEB band was identified. The pSEB was approximately 3,500 daltons larger than extracellular SEB. This component was purified by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two-dimensional peptide maps of the putative SEB precursor revealed that most of the tryptic peptides were identical to those of mature extracellular SEB. When purified membranes of other SEB+ (DU4916 and 10-275) and SEB- (RN450, RN451, S6R, and FR1100) S. aureus strains were analyzed by the nitrocellulose blot procedure, only the SEB+ strains contained this putative SEB precursor on their membranes.