A two-dimensional electrophoresis technique for protein separation has been developed, offering high resolution and sensitivity for analyzing proteins from complex biological sources. Proteins are separated first by isoelectric focusing based on their isoelectric point, and then by SDS-PAGE based on molecular weight. This method allows for the almost uniform distribution of protein spots across a two-dimensional gel. It can resolve up to 5000 proteins, with the ability to detect as little as one disintegration per minute of ¹⁴C or ³³S. Proteins as low as 10⁻⁴ to 10⁻⁵% of the total protein can be detected and quantified. The technique is highly reproducible, allowing for matching of spots between different separations. It can detect proteins differing in a single charge and identify missense mutations affecting charge. The method is described in detail, along with the materials and procedures used. The technique involves the use of polyacrylamide gels, with isoelectric focusing in the first dimension and SDS-PAGE in the second. The gels are prepared using specific buffers and solutions, and proteins are labeled with radioactive isotopes for detection. Sample preparation involves lysing cells, treating with enzymes, and dissolving in lysis buffer. The first dimension gel is prepared with urea and ampholines, and the second dimension gel is made with acrylamide and SDS. The gels are run under specific conditions, and the results are stained and analyzed. The technique allows for the separation of over 1000 proteins from E. coli, with the ability to detect and quantify proteins as low as 10⁻⁴ to 10⁻⁵% of the total. The resolution of the technique is limited by the properties of the sample, with the ability to detect minor components requiring overexposure. The technique is highly sensitive, with the ability to detect proteins as low as 0.01 µg using Coomassie blue staining. Autoradiography is used to detect proteins with as little as 1 cpm. The technique is reproducible, with the ability to match spots between different separations. The resolution of the technique is limited by the diffusion of proteins during equilibration and the properties of the sample. The technique is useful for analyzing proteins in complex biological systems and detecting trace components. The method is described in detail, along with the materials and procedures used.A two-dimensional electrophoresis technique for protein separation has been developed, offering high resolution and sensitivity for analyzing proteins from complex biological sources. Proteins are separated first by isoelectric focusing based on their isoelectric point, and then by SDS-PAGE based on molecular weight. This method allows for the almost uniform distribution of protein spots across a two-dimensional gel. It can resolve up to 5000 proteins, with the ability to detect as little as one disintegration per minute of ¹⁴C or ³³S. Proteins as low as 10⁻⁴ to 10⁻⁵% of the total protein can be detected and quantified. The technique is highly reproducible, allowing for matching of spots between different separations. It can detect proteins differing in a single charge and identify missense mutations affecting charge. The method is described in detail, along with the materials and procedures used. The technique involves the use of polyacrylamide gels, with isoelectric focusing in the first dimension and SDS-PAGE in the second. The gels are prepared using specific buffers and solutions, and proteins are labeled with radioactive isotopes for detection. Sample preparation involves lysing cells, treating with enzymes, and dissolving in lysis buffer. The first dimension gel is prepared with urea and ampholines, and the second dimension gel is made with acrylamide and SDS. The gels are run under specific conditions, and the results are stained and analyzed. The technique allows for the separation of over 1000 proteins from E. coli, with the ability to detect and quantify proteins as low as 10⁻⁴ to 10⁻⁵% of the total. The resolution of the technique is limited by the properties of the sample, with the ability to detect minor components requiring overexposure. The technique is highly sensitive, with the ability to detect proteins as low as 0.01 µg using Coomassie blue staining. Autoradiography is used to detect proteins with as little as 1 cpm. The technique is reproducible, with the ability to match spots between different separations. The resolution of the technique is limited by the diffusion of proteins during equilibration and the properties of the sample. The technique is useful for analyzing proteins in complex biological systems and detecting trace components. The method is described in detail, along with the materials and procedures used.