Studying the mechanical unfolding of biopolymers (molecular elasticity) provides important information about their mechanical stability and energy landscape. This is especially important in proteins, since their three-dimensional structure is essential for their correct activity.

In this work, the researchers of the Institute of Biophysics discuss the preparation of polyprotein constructs suitable for single molecule force spectroscopy experiments (SMFS) with atomic force microscopy (AFM), as well as the models and equations employed in the analysis of the unfolding data. As a practical example, they show the results obtained with a homopolyprotein containing nine repeats of the I27 domain from the muscle protein titin.

An example of a force-vs-distance curve obtained in their SMFS-AFM experiments can be observed in the attached image. The protein construct is adsorbed to freshly gold-coated coverslips. Then the tip and the sample are brought into contact. The protein construct adheres to the tip, which is retracted from the surface at a constant speed. Thus, a characteristic saw-tooth-like pattern (corresponding to unfolding events) in the force-vs-distance trace can be observed

An article by: Juan Carlos Gil-Redondo, Andreas Weber and José Luis Toca-Herrera

Microscopy Research and Technique, Mai 2022, https://doi.org/10.1002/jemt.24136

Read all:

Part 1: Measuring biomaterials mechanics with atomic force microscopy. 1. Influence of the loading rate and applied force (pyramidal tips)

Part 2: Measuring (biological) materials mechanics with atomic force microscopy. 2. Influence of the loading rate and applied force (colloidal particle

Part 3: Measuring (biological) materials mechanics with atomic force microscopy. 3. Mechanical unfolding of biopolymers