AVS 57th International Symposium & Exhibition
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeA

Paper BI-WeA10
Secondary Structures of Soft- and Reactively Landed Multiply Charged Protein Ions

Wednesday, October 20, 2010, 5:00 pm, Room Taos

Session: Proteins & Peptides on Surfaces
Presenter: Q. Hu, Pacific Northwest National Laboratory
Authors: Q. Hu, Pacific Northwest National Laboratory
P. Wang, Pacific Northwest National Laboratory
J. Laskin, Pacific Northwest National Laboratory
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Soft- and reactive landing of mass-selected ions enables highly selective preparation of uniform thin films of a variety of complex molecules on surfaces. We previously demonstrated that conformationally-selected peptide arrays can be prepared using SL of peptide ions onto self-assembled monolayer (SAM) surfaces. In this work we studied the secondary structures of protein ions soft- and reactively landed onto SAM surfaces using infrared reflection absorption spectroscopy (IRRAS). Different charge states of ubiquitin were generated by electrospray ionization (ESI). The structure of the low charge state corresponds to the pseudo-native state of the protein and the high charge state corresponds to an unfolded state. Inert CH3-terminated SAM (HSAM) and hydrophilic COOH-terminated SAM (COOH-SAM) were used as soft- landing targets. Detailed analysis of IRRAS spectra, especially the amide I band, provides valuable information on the secondary structures of the immobilized protein species. This technique allows us to study the effect of the initial conformation and the properties of the surface on the secondary structure of immobilized proteins. Secondary structure of ubiquitin ions reactively landed onto SAM of N-hydroxysuccinimidyl ester terminated alkylthiol on gold (NHS-SAM) was also studied by IRRAS, and the reaction rate was determined from the depletion of the strong asymmetric carbonyl stretching band of the NHS group.