Proteomics: The Next Frontier-A Biotech Perspective.
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Biomedical subjects
Publications and source records attributed to M. Walid Qoronfleh.
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The human proteome project will demand faster, easier, and more reliable methods to isolate and purify protein targets. Membrane proteins are the most valuable group of proteins since they are the target for 70-80% of all drugs. Perbio Science has developed a protocol for the quick, easy, and reproducible isolation of integral membrane proteins from eukaryotic cells. This procedure utilizes a proprietary formulation to facilitate cell membrane disruption in a mild, nondenaturing environment and efficiently solubilizes membrane proteins. The technique utilizes a two-phase partitioning system that enables the class separation of hydrophobic and hydrophilic proteins. A variety of protein markers were used to investigate the partitioning efficiency of the membrane protein extraction reagents (Mem-PER) (Mem-PER is a registered trademark of Pierce Biotechnology, Inc) system. These included membrane proteins with one or more transmembrane spanning domains as well as peripheral and cytosolic proteins. Based on densitometry analyses of our Western blots, we obtained excellent solubilization of membrane proteins with less than 10% contamination of the hydrophobic fraction with hydrophilic proteins. Compared to other methodologies for membrane protein solubilization that use time-consuming protocols or expensive and cumbersome instrumentation, the Mem-PER reagents system for eukaryotic membrane protein extraction offers an easy, efficient, and reproducible method to isolate membrane proteins from mammalian and yeast cells.
Immunoprecipitation (IP) and coimmunoprecipitation (co-IP) are key techniques for studying protein-protein interactions. These methods utilize immobilized protein A or protein G to isolate antibody-bound target antigens. The main disadvantage of traditional immunoprecipitation and coimmunoprecipitation is that the conditions used to elute the precipitated antigen also release the antibody, contaminating the antigen and destroying the antibody support. To overcome these problems, we describe two methods to generate a reusable antibody support by cross-linking the antibody to immobilized protein A or protein G, or by coupling it directly to the resin. Our studies have demonstrated that the immobilization efficiency for the antibody coupling method was similar for several species of antibody. Furthermore, we illustrate that using both methods of antibody immobilization yields IP and co-IP results similar to traditional protocols but eliminate the antibody heavy and light chains contamination.