Crystalline chitin hydrolase is a burnt-bridge Brownian motor

Motility of an autonomous protein-based artificial motor that operates via a burnt-bridge principle

Inspired by biology, great progress has been made in creating artificial molecular motors. However, the dream of harnessing proteins - the building blocks selected by nature - to design autonomous motors has so far remained elusive. Here we report the synthesis and characterization of the Lawnmower, an autonomous, protein-based artificial molecular motor comprised of a spherical hub decorated with proteases. Its "burnt-bridge" motion is directed by cleavage of a peptide lawn, promoting motion towards unvisited substrate. We find that Lawnmowers exhibit directional motion with average speeds of up to 80 nm/s, comparable to biological motors. By selectively patterning the peptide lawn on microfabricated tracks, we furthermore show that the Lawnmower is capable of track-guided motion. Our work opens an avenue towards nanotechnology applications of artificial protein motors.

Editors’ Roundup: April 2022

This Commentary represents the first instalment of a regular feature that seeks to fulfil one of Biophysical Reviews' IUPAB mandated goals-that of assisting in the international promotion of biophysical research. Known as the 'Editors' Roundup', this Commentary feature is a multi-author collective description of recently published research from journals publishing material across the biophysical realm. Although Biophysical Reviews is published by Springer-Nature, the source of contributed articles is unrestricted and can include different commercial and society publishers. In this edition we have article descriptions from the following journals, Biophysical Reviews, Biophysics and Physicobiology and Cell Biochemistry and Biophysics.

Label-free monitoring of crystalline chitin hydrolysis by chitinase based on Raman spectroscopy

We demonstrate a method for label-free monitoring of hydrolytic activity of crystalline-chitin-degrading enzyme, chitinase, by means of Raman spectroscopy. We found that crystalline chitin exhibited a characteristic Raman peak at 2995 cm-1, which did not appear in the reaction product, N,N'-diacetylchitobiose. We used this Raman peak as a marker of crystalline chitin degradation to monitor the hydrolytic activity of chitinase. When the crystalline chitin suspension and chitinase were mixed together, the peak intensity of crystalline chitin at 2995 cm-1 was linearly decreased depending on incubation time. The decrease in peak intensity was inversely correlated with the increase in the amount of released N,N'-diacetylchitobiose, which was measured by conventional colorimetric assay with alkaline ferricyanide. Our result, presented here, provides a new method for simple, in situ, and label-free monitoring of enzymatic activity of chitinase.