Single molecule mechanical manipulation for studying biological properties of proteins, DNA, and sugars

For over 20 years there has been immense biological insight gained using single molecule mechanical measurements to understand properties of biomolecules. This review outlines the field of single molecule mechanics studies and focuses on the manipulation of proteins, DNA, and sugars by single molecule force spectroscopy (SMFS) by atomic force microscopy (AFM). The methods and examples of SMFS by AFM are illustrated using recent advances in protein science including titin elasticity, mechanical unfolding and refolding of α-helical repeat proteins, mechanoenzymatics of thioredoxin and titin kinase, and intermolecular interactions of P-selectin complexes. The possibilities of SMFS to investigate the mechanics of other biopolymers like double- and single-stranded DNA and forced-induced conformational changes in sugars are also discussed. Finally, SMFS and its application to biological processes, like DNA replication, packing and transcription, and DNA methylation are illustrated. These measurements provide a unique and integral part of the development of our knowledge of biochemistry and molecular mechanics.