Bovine serum albumin, the main component of blood (38g/1000ml), molecular weight 68kD. Isoelectric point 4.8. Nitrogen content 16%, sugar content 0.08%. It contains only hexose and hexosamine, and contains only 0.2% fat. Albumin consists of 581 amino acid residues, among which 35 cysteines form 17 disulfide bonds and there is a free sulfhydryl group at the 34th position of the peptide chain. Albumin can bind to a variety of cations, anions and other small molecules. The albumin in blood mainly plays the role of maintaining osmotic pressure, PH buffering, carrier and nutrition. In serum-free culture of animal cells, the addition of albumin can play a physiological and mechanical protective and carrier role. Bovine Serum albumin (BSA), also known as the fifth component, is a globulin in bovine serum containing 583 amino acid residues, with a molecular weight of 66.430 Da and an isoelectric point of 4.7. Bovine serum albumin is widely used in biochemical experiments.