Mechanism of hen egg white lysozyme adsorption on a charged solid surface

Karina Kubiak-Ossowska, Paul A. Mulheran

Research output: Contribution to journalArticle

74 Citations (Scopus)

Abstract

The mechanism of hen egg white lysozyme (HEWL) adsorption on a negatively charged, hydrophilic surface has been studied using atomistic molecular dynamics (MD) simulation. Sixteen 90 ns trajectories provide adequate data to allow a detailed description of the adsorption process to be formulated. Two distinct adsorption sites have been identified. The main one is located on the N,C-terminal protein face and comprises Arg128 (the crucial one), supplemented by Arg125, Arg5, and Lys1; the minor one is used accidentally and contains only Arg68. Adsorption of this protein is driven by electrostatics, where the orientation of the protein dipole moment defines the direction of protein movement. The diffusion range on the surface depends on protein side-chain penetration through the surface water layers. This is facilitated by the long-range electric field of the charged surface, which can align polar side chains to be perpendicular to the surface. A simulation of adsorption onto a neutral ionic surface shows no such surface water layer penetration. Therefore, protein flexibility is seen to be an important factor, and to adsorb the HEWL has to adjust its structure. Nevertheless, at a flat surface only a slight loss of alpha-helical content is required. The adsorbed HEWL molecule is oriented between side-on and end-on ways, where the angle between the protein long axis (which mostly approximates the dipole moment) and the surface varies between 45 degrees and 90 degrees. Simulations with targeted mutations confirm the picture that emerges from these studies. The active site is located on the opposite face to the main adsorption site; hence, the activity of the immobilized HEWL should not be affected by the surface interactions. Our results provide a detailed insight into the adsorption mechanism and protein mobility at the surface. This knowledge will aid the proper interpretation of experimental results and the design of new experiments and functional systems.

LanguageEnglish
Pages15954-15965
Number of pages12
JournalLangmuir
Volume26
Issue number20
DOIs
Publication statusPublished - 19 Oct 2010

Fingerprint

eggs
lysozyme
Muramidase
solid surfaces
Enzymes
proteins
Adsorption
adsorption
Proteins
surface water
Dipole moment
Surface waters
dipole moments
penetration
simulation
mutations
surface reactions
flat surfaces
Design of experiments
flexibility

Keywords

  • atomic force microscopy
  • silica-water interface
  • protein adsorption
  • conformational changes
  • binding orientation
  • molecular dynamics
  • neutron reflection
  • albumin adsorption
  • hydroxyapatite
  • MICA

Cite this

Kubiak-Ossowska, Karina ; Mulheran, Paul A. / Mechanism of hen egg white lysozyme adsorption on a charged solid surface. In: Langmuir. 2010 ; Vol. 26, No. 20. pp. 15954-15965.
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Mechanism of hen egg white lysozyme adsorption on a charged solid surface. / Kubiak-Ossowska, Karina; Mulheran, Paul A.

In: Langmuir, Vol. 26, No. 20, 19.10.2010, p. 15954-15965.

Research output: Contribution to journalArticle

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KW - MICA

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