BSA, SANS, folding-unfolding, three-dimensional structure, pH dependent


The pH-dependent structures of the bovine serum albumin (BSA), under physiological conditions that permit enzymatic activity, were investigated by small-angle neutron scattering (SANS). The unfolding behavior of BSA in solution is important to understand the mechanism of protein aggregation due to protein conformational change. The information of protein structure is crucial to design the perfect protein-based drug delivery device. This information will be useful as a complementary data of BSA crystal structure in static state. The structure of BSA in solution was found to be heart shaped, nearly identical to bovine serum albumin crystal structure. The globular heart shaped structure of BSA was still maintained at alkaline pH range of 7 to 11. It underwent partial unfolding at pH 5 and continued to unfold at pH 3. The unfolded-structure of BSA shows that the globular structure started to change into a cylinder-like structure at pH 3 which was clearly shown in Kratky plot. These results were confirmed with ab initio low-resolution shape calculation model analysis using GNOM and DAMMIF in obtaining the three-dimensional protein structure model.


Wu, Y., Cheng, H., Chen, Y., Chen, L., Fang, Z., and Liang, L. , 2017, Formation of a Multiligand Complex of Bovine Serum Albumin with Retinol, Resveratrol, and (-)-Epigallocatechin-3-gallate for the Protection of Bioactive Components, . J. Agric. Food Chem. 65, 3019–3030. Available at:

Tian, R., Long, X., Yang, Z., Lu, N., and Peng, Y.Y. , 2020, Formation of a bovine serum albumin diligand complex with rutin and single-walled carbon nanotubes for the reduction of cytotoxicity, . Biophys. Chem. 256, 106268. Available at:

Zhang, Y., Sun, T., and Jiang, C. , 2018, Biomacromolecules as carriers in drug delivery and tissue engineering, . Acta Pharm. Sin. B 8, 34–50. Available at:

Gharbavi, M., Manjili, H.K., Amani, J., Sharafi, A., and Danafar, H. , 2019, In vivo and in vitro biocompatibility study of novel microemulsion hybridized with bovine serum albumin as nanocarrier for drug delivery, . Heliyon 5, e01858. Available at:

Afridi, M.N., Lee, W.H., and Kim, J.O. , 2020, Application of synthesized bovine serum albumin-magnetic iron oxide for phosphate recovery, . J. Ind. Eng. Chem. 86, 113–122. Available at:

FOSTER, J.F. , 1977, Some Aspects of the Structure and Conformational Properties of Serum Albumin, (Pergamon Press Inc.) Available at:

Raskin, J., Cummings, J., Hardy, J., Schuh, K., and Dean, R. , 2015, Neurobiology of Alzheimer’s Disease: Integrated Molecular, Physiological, Anatomical, Biomarker, and Cognitive Dimensions, . Curr. Alzheimer Res. 12, 712–722. Available at:

Olanow, C.W., and Tatton, W.G. , 1999, Etiology and Pathogenesis of Parkinson Disease, . Neurol. Clin. 22, 123–144. Available at:

Majorek, K.A., Porebski, P.J., Dayal, A., Zimmerman, M.D., Jablonska, K., Stewart, A.J., Chruszcz, M., and Minor, W. , 2012, Structural and immunologic characterization of bovine, horse, and rabbit serum albumins, . Mol. Immunol. 52, 174–182. Available at:

Jacques, D. a., and Trewhella, J. , 2010, Small-angle scattering for structural biology - Expanding the frontier while avoiding the pitfalls, . Protein Sci. 19, 642–657. Available at:

Dewhurst, C. , 2003, GRASP User Manual, . Tech. Rep. No. ILL03DE01T. Available at:

Kline, S.R. , 2006, Reduction and analysis of SANS and USANS data using IGOR Pro, . J. Appl. Crystallogr. 39, 895–900. Available at:

Doniach, S. , 2001, Changes in biomolecular conformation seen by small angle X-ray scattering, . Chem. Rev. 101, 1763–1778. Available at:

Petoukhov, M. V., Franke, D., Shkumatov, A. V., Tria, G., Kikhney, A.G., Gajda, M., Gorba, C., Mertens, H.D.T., Konarev, P. V., and Svergun, D.I. , 2012, New developments in the ATSAS program package for small-angle scattering data analysis, . J. Appl. Crystallogr. 45, 342–350. Available at:

Svergun, D.I., Petoukhov, M. V, and Koch, M.H. , 2001, Determination of domain structure of proteins from X-ray solution scattering., . Biophys. J. 80, 2946–2953. Available at:

Franke, D., and Svergun, D.I. , 2009, DAMMIF, a program for rapid ab-initio shape determination in small-angle scattering, . J. Appl. Crystallogr. 42, 342–346. Available at:

Svergun, D.I. , 1999, Restoring low resolution structure of biological macromolecules from solution scattering using simulated annealing., . Biophys. J. 76, 2879–86. Available at:

Ahmad, B., Kamal, M.Z., and Khan, R.H. , 2004, Alkali-induced conformational transition in different domains of bovine serum albumin., . Protein Pept. Lett. 11, 307–315. Available at:

Sadler, P.J., and Tucker, A. , 1993, pH-induced structural transitions of bovine serum albumin. Histidine pKa values and unfolding of the N-terminus during the N to F transition., . Eur. J. Biochem. 212, 811–7. Available at:

Kun, R., Szekeres, M., and Dekany, I. , 2009, Isothermal titration calorimetric studies of the pH induced conformational changes of bovine serum albumin, . J. Therm. Anal. Calorim. 96, 1009–1017. Available at:

Serum, B. , 1954, Bovine Serum Albumin and its Behaviour in Acid Solution, . Biochem.J. 62, 569–582.






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