Viscoelasticity of the folded domain of a single protein at varying frequencies

Abstract

nderstanding the mechanics of folded single proteins help us understand several biological pro cesses. One of the established methods is Single-molecule force spectroscopy. The conformational stability of a folded state which allows the protein to adopt different shapes and perform functions can be characterised by its viscoelasticity. Pulling the single protein and observing its nanome chanical response can provide insight into its functioning. We use sequentially arranged 8 domains I-27 the immunoglobulins (IgG) of titin and measure its stiffness and internal friction to understand the mechanics of a folded single protein. We will use a special interferometer-based atomic force microscope for direct and simultaneous measurement of stiffness and internal friction. In addition to this, we will also perform the unfolding of titin (I-27) protein at higher pulling frequencies and micro-sec-time resolution using high-speed force spectroscopy. In this project, we will perform protein unfolding at different frequencies. We will use interferometer-based AFM to pull the pro tein at different frequencies ranging from 100 Hz to 2 kHz and HS AFM to go further to 100 kHZ. The direct measurement of stiffness and friction of folded states has been recently established us ing special interferometer-based AFM but not at several ranges of pulling rates and frequencies. We will compare the data we get from interferometer-based AFM and high-speed AFM. The aim of this project is: 1. Directly measuring the stiffness and internal friction of folded states of single protein at ranging frequencies. k 2. Comparing the results of protein pulling of interferometer-based AFM and high-speed AFM