The ability to orient proteins on surfaces, to control exposure of their biologically active sites, will benefit a wide range of applications. In this study, we examined the change in orientation of horse heart Cytochrome c on both NH3+ and COO- self-assembled monolayers by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and sum frequency generation (SFG) spectroscopy. The positively charged region at one end Cytochrome c electrostatically binds to the COO- substrate while the NH3+ surface elicits the opposite binding orientation. Within the SFG spectra, ordering of the alpha helices within the protein was confirmed by the feature at 1645 cm-1 and this change in orientation, induced by the two different substrates, is confirmed by intensity differences within ToF-SIMS spectra between ions stemming from asymmetric distributed amino acids (Glutamic acid, Aspartic acid).

Determining the orientation of electrostatically immobilized cytochrome C by time-of-flight secondary ion mass spectrometry and sum frequency generation

243rd National Meeting (2012)

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