Protein A vs Protein G, what is the difference? They are both bacterial cell wall proteins that have primary binding sites for mammalian immunoglobulin G (IgG) antibodies, including human IgG. Protein G was first isolated from Streptococcal bacteria strains C and G. Similarly, protein A was originally found on the cell wall of the bacteria Staphylococcus aureus. These proteins have primary binding domains for the Fc region of (IgG) antibodies, but can also recognize the Fab region of certain IgG subclasses described in more detail below.. For the bacteria this is useful because binding IgG’s at the Fc region prevents macrophages from recognizing them, which in turn prevents phagocytosis of the invading bacteria by the host immune system. For scientists this IgG binding can be used for probing in experiments such as purifications or immunoprecipitations.
These complexes of magnetic beads and their bound materials are then separated from a complex mixture in solution with a magnetic separation rack. The result is an isolated solution of your target biological elements which can be enriched and concentrated through this process.
The purification of RNA is important for research laboratories and clinics. Throughout the COVID19 pandemic, the purification of RNA has been in the news because the rate of RNA purification defines how quickly testing for COVID19 can be done. RNA is now in the news again, mRNA specifically, as major companies have developed mRNA vaccines for COVID19. In brief, the vaccine is an injection that sends lipid coated mRNA into cells. In cells, the mRNA is translated into the spike protein of SARS-CoV-2. Companies have shown robust responses to the vaccines as the creation of the protein in cells elicits a good amount of response from the correct immune cells.
Filtration is a simple technique used to separate solid particles from suspension in a liquid solution. There are many filtration methods available, but all are based on the same general principle: a heterogenous mixture is poured over a filter membrane. The filter membrane has pores of a particular size. Particles larger than the pores will be unable to pass through the membrane, while particles smaller than the pores will pass through unhindered. Additionally, all liquids will pass through. The final result of a filtration process is a collection of residue on the filtration membrane. This residue is therefore effectively separated from the rest of the mixture that passed through the membrane.