Adsorption Behavior ofHydrophobin Proteins on PolydimethylsiloxaneSubstrates.

The design of a bioactive surface with appropriate wettabilityfor effective protein immobilization has attracted much attention.Previous experiments showed that the adsorption of hydrophobic proteinHFBI onto a polydimethylsiloxane (PDMS) substrate surface can reversethe inherent hydrophobicity of the surface, hence making it suitablefor immobilization of a secondary protein. In this study, atomisticmolecular dynamics simulations have been conducted to elucidate theadsorption mechanism of HFBI on the PDMS substrate in an aqueous environment.Nine independent simulations starting from three representative initialorientations of HFBI toward the solid surface were performed, resultingin different adsorption modes. The main secondary structures of theprotein in each mode are found to be preserved in the entire courseof adsorption due to the four disulfide bonds. The relative bindingfree energies of the different adsorption modes were calculated, showingthat the mode, in which the binding residues of HFBI fully come fromits hydrophobic patch, is most energetically favored. In this favorablebinding mode, the hydrophilic region of HFBI is fully exposed to water,leading to a high hydrophilicity of the modified PDMS surface, consistentwith experiments. Furthermore, a set of residues consisting of Leu12,Leu24, Leu26, Ile27, Ala66, and Leu68 were found to play an importantrole in the adsorption of HFBI on different hydrophobic substrates,irrespective of the structural features of the substrates. [ABSTRACT FROM AUTHOR]