Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (04): 849-857.doi: 10.3866/PKU.WHXB201301182

• BIOPHYSICAL CHEMISTRY • Previous Articles     Next Articles

Standing Orientation of Lysozymes Induced by Electrostatically Repulsive Surface

BAI Shu1,2, LI Hao1,2, ZHANG Lin1,2   

  1. 1 Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China;
    2 Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin 300072, P. R. China
  • Received:2012-10-22 Revised:2013-01-15 Published:2013-03-25
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21236005, 21006069) and Innovation Foundation of Tianjin University, China.

Abstract:

Inhibition of protein aggregation during protein refolding is a fundamental issue in the production of recombinant therapeutic proteins. It has recently been experimentally found that like-charged ion-exchange resin can suppress the aggregation of folding intermediates through electrostatic repulsion. However, the microscopic understanding of this process is far from adequate, and it is difficult to examine the microscopic process using experimental approaches. Molecular dynamics (MD) simulation is a powerful tool which can provide clear microscopic information in a direct manner. Therefore, in the present study, a model of an electrostatically repulsive surface is constructed to simulate the like-charged ion-exchange resin. The distribution of lysozyme molecules near the surface is then investigated using MD simulation with all-atom (AA) models and the effect of the charge number of the surface is examined. It is found that the protein is excluded from the surface by electrostatic repulsion. During this process, the protein molecule becomes standing, where the dipole of the protein is perpendicular to the surface. When the protein moves far from the surface, diminished oriented alignment is observed due to the decreased electrostatic repulsion from the surface. It is also found that better oriented alignment on the surface occurs with higher charge number. The simulation results thus provide microscopic information about the alignment of protein molecules near an electrostatically repulsive surface, and are expected to be helpful for investigation of protein refolding on charged surfaces and the molecular interactions involved.

Key words: Interfacial behavior, Microscopic information, Charge number, Conformation, Molecular dynamics simulation

MSC2000: 

  • O641