Probing Globular Protein Self-Assembling Dynamics by Heterodyne Transient Grating Experiments

Sara Catalini,Paolo Foggi,Paolo Bartolini,Renato Torre,Andrea Taschin

doi:10.3390/app9030405

Sara Catalini, Paolo Foggi + Show 3 more

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https://doi.org/10.3390/app9030405

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Journal: Applied Sciences	Publication Date: Jan 25, 2019
Citations: 4	License type: CC BY 4.0

Affiliation: University of Florence, University of Perugia

Abstract

In this work, we studied the propagation of ultrasonic waves of lysozyme solutions characterized by different degrees of aggregation and networking. The experimental investigation was performed by means of the transient grating (TG) spectroscopy as a function of temperature, which enabled measurement of the ultrasonic acoustic proprieties over a wide time window, ranging from nanoseconds to milliseconds. The fitting of the measured TG signal allowed the extraction of several dynamic properties, here we focused on the speed and the damping rate of sound. The temperature variation induced a series of processes in the lysozyme solutions: Protein folding-unfolding, aggregation and sol–gel transition. Our TG investigation showed how these self-assembling phenomena modulate the sound propagation, affecting both the velocity and the damping rate of the ultrasonic waves. In particular, the damping of ultrasonic acoustic waves proved to be a dynamic property very sensitive to the protein conformational rearrangements and aggregation processes.

Highlights

In order to fulfill protein functions, the polypeptide chains must be organized in their native conformation
We investigated the propagation of ultrasonic acoustic waves in the lysozyme solution and hydrogel, by heterodyne transient grating (HD-TG) spectroscopy [28]
We have studied the acoustic properties of lysozyme aqueous systems at a wave vector of

Summary

Introduction

In order to fulfill protein functions, the polypeptide chains must be organized in their native conformation. Erroneous protein structuring (misfolding) may occur, resulting in the onset of many diseases [1]. The development of protein structural organization is given by the tendency to minimize interactions between the hydrophobic residues and the polar solvent. It is possible to modulate the protein’s unfolding and aggregation processes by changing the environmental conditions, such as pH, ionic strength, solvent composition and temperature. These self-assembling phenomena are characterized by different steps, in which the protein undergoes conformational rearrangements and intermolecular associations to form stable structures of increasing complexity [2,3], such as amyloid fibrils and hydrogel networks [4,5]

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