本文格式为Word版，下载可任意编辑BSA牛血清白蛋白 导读： 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测验中有广泛的应用，例如在western blot中作为Blocking agent The full-l 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测验中有广泛的应用，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 (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] BSA牛血清白蛋白 Diffusion constant, D20,W 107 cm2/s: 5.9[5][4] Partial specific volume, V20: 0.733[5][4] Intrinsic viscosity, η: 0.0413[5][4] Frictional ratio, f/f0: 1.30[5][4] Refractive index increment (578 nm) 10-3: 1.90[5][4] Optical absorbance, A279nm1 g/L: 0.667[5][4] Mean residue rotation, [m']233: 8443[5][4] Mean residue ellipticity: 21.1 [θ]209 nm; 20.1 [θ]222 nm[5][4] Estimated a-helix, %: 54[5][4] Estimated b-form, %: 18[5][4] BSA has numerous biochemical applications including ELISAs (Enzyme-Linked Immunosorbent Assay), immunoblots, and immunohistochemistry. It is also used as a nutrient in cell and microbial culture.[citation needed] In restriction digests, BSA is used to stabilize some enzymes during digestion of DNA and to prevent adhesion of the enzyme to reaction tubes, pipet tips, and other vessels.[7] This protein does not affect other enzymes that do not need it for stabilization. BSA is also commonly used to determine the quantity of other proteins, by comparing an unknown quantity of protein to known amounts of BSA (see Bradford protein assay). BSA is used because of its stability to increase signal in assays, its lack of effect in many biochemical reactions, and its low cost, since large quantities of it can be readily purified from bovine blood, a byproduct of the cattle industry. — 4 —。