The impact that protein secondary structure may have on protein adsorption has been, hitherto, largely unstudied. To this end, secondary structures (a-helix, �-sheet) were induced in Poly L-Lysine (PLL) via modulating solution pH and temperature. Circular dichroism (CD) and quartz crystal microbalance with dissipation (QCM-D) were used to study adsorption of PLL to Au surfaces. CD results confirmed that secondary structures (a-helix, �-sheet) persist upon adsorption onto Au. QCM-D revealed: (1) initial adsorption rates for a-helix was ~2.4 times higher than �-sheet; (2) plateau adsorbed amount was ~4.6 times more for �-sheet than a-helix; and (3) fitted viscosities suggest a-helix forms a more rigidly bonded layer on Au. Surface interactions between PLL and Au were analyzed by DLVO theory, predicting the ratio of interaction energies for �-sheet and a-helix to Au as ~0.36, which is in good agreement with experimentally estimated value ~0.41 based on initial adsorption rates from QCM-D measurements.

Secondary structure effects on peptide adsorption

243rd National Meeting (2012)

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