Studies of Affinity Protein Captured at G‐quadruplex DNA‐modified surfaces

This talk will focus on the investigation of the mechanism that govern the affinity protein capture at DNA‐modified surfaces using multiple experimental techniques including affinity MALDI‐mass spectrometry (MALDI‐MS), scanning electron microscope (SEM), Atomic Force Microscopy (AFM) and surface Plasmon resonance (SPR). The DNA oligonucleotides we are using are sequences from promoter region of human genes that can form a three‐dimensional DNA structure called the G‐quadruplex (G4). The oligonucleotides are attached to indium tin oxide‐coated glass plates for affinity MALDI‐MS and to streptavidinated magnetic beads for protein collection. Individual protein and nuclear extracts from human cell lines are incubated with the modified surfaces, followed by rinsing to remove non‐specifically bound proteins and concomitants. In affinity MALDI‐MS, the remaining, bound proteins are detected directly at the surface by MALDI‐MS. The proteins captured by the affinity beads are collected for further analysis and identification by mass spectrometry. SEM and AFM are used to image the surfaces before and after oligonucleotide attachment and after protein capture. SPR is used to study the binding affinities and on‐off kinetics of the binding interactions.