BSA牛血清白蛋白

Bovine serum albumin

牛血清白蛋白（BSA），又称第五组分，是牛血清中的一种球蛋白，包含583个氨基酸残基，分子量为66.430 kDa，等电点为4.7。牛血清白蛋白在生化实验中有广泛的应用，例如在western blot中作为Blocking agent。

The full-length BSA precursor protein is 607 amino acids(AAs) in length. An N-terminal 18-residue signal peptide is cut off from the precursor protein upon secretion, hence the initial protein product contains 589 amino acid residues. An additional 4 amino acids are cleaved to yield the mature BSA protein that contains 583 amino acids.

Physical properties of BSA:

Number of amino acid residues: 583 Molecular weight: 66,463 Da (= 66.5 kDa) isoelectric point in water at 25 °C: 4.7[1] Extinction coefficient of 43,824 M 1cm 1 at 279 nm[2] Dimensions: 140 × 40 × 40 Å (prolate ellipsoid where a = b < c)[3] pH of 1% Solution: 5.2-7 [4][5] [5][4]Optical Rotation: [α]259: -61°; [α]264: -63° Stokes Radius (rs): 3.48 nm[6] Sedimentation constant, S20,W × 1013: 4.5 (monomer), 6.7 (dimer)[5][4]