Bovine Serum Albumin (BSA) is a widely utilized protein in scientific research. Its versatility stems from its unique biochemical properties, making it indispensable in laboratory applications. Sigma-Aldrich, a prominent global supplier, provides a wide array of BSA products for the scientific community.
Understanding Bovine Serum Albumin
Bovine Serum Albumin is a globular protein derived from cow blood plasma, making up approximately 50-60% of the total protein content. The mature BSA protein consists of 583 amino acids and has a molecular weight of approximately 66.5 kDa. Its structure includes three homologous domains, each divided into two sub-domains, which contribute to its diverse binding capabilities.
BSA is highly soluble in water and maintains stability across a range of pH levels (typically pH 4 to 9) and temperatures (up to 60 °C). It is relatively inert, meaning it generally does not interfere with biological reactions, making it suitable for sensitive assays. The protein also contains 17 disulfide bridges that help stabilize its overall structure.
Diverse Applications in Science
BSA’s unique characteristics allow for its widespread application in scientific research. One primary use is as a blocking agent in immunoassays like ELISA (Enzyme-Linked Immunosorbent Assay), Western blotting, and immunohistochemistry. In these techniques, BSA coats unoccupied binding sites on laboratory surfaces, preventing non-specific attachment of antibodies or other proteins that could lead to false positive results or high background noise.
BSA also serves as a reliable protein standard for quantifying protein concentrations, notably in methods such as the Bradford assay. In this colorimetric assay, Coomassie Brilliant Blue dye binds to proteins, causing a color change that can be measured spectrophotometrically. Researchers create a standard curve using known concentrations of BSA to accurately determine the protein content of unknown samples.
BSA also acts as a stabilizer for sensitive biological molecules, including enzymes and antibodies. It prevents these proteins from denaturing, aggregating, or adhering to the walls of reaction tubes and pipette tips, thereby extending their shelf life and maintaining their activity during experiments. BSA can also be incorporated into cell culture media as a nutrient supplement, providing essential fatty acids, hormones, and peptides that support cell growth and viability, particularly in serum-free conditions. Its ability to bind and transport hydrophobic molecules, such as fatty acids, hormones, and drugs, further expands its utility as a carrier protein in various biochemical studies.
BSA and Sigma-Aldrich’s Role
Sigma-Aldrich plays a significant role in supplying BSA to the global scientific community. They offer a diverse range of BSA products for various research and manufacturing needs. These products come in different grades and purities, such as Fraction V, a highly purified form typically greater than 98% purity and free from other detectable proteins or contaminants.
Other specialized BSA preparations include protease-free grades, important for applications where enzyme degradation of other proteins must be avoided, and low endotoxin grades, suitable for cell culture applications where endotoxin contamination could negatively impact cell health. The availability of these purities ensures researchers can select the most appropriate BSA, contributing to reliable and consistent scientific results. Consistent sourcing by major suppliers like Sigma-Aldrich is important for reproducibility and advancement in scientific endeavors.