Editing Force spectroscopy (section)

==Applications==
{{More citations needed section|date=May 2014|talk=Anchor}}
Common applications of force spectroscopy are measurements of [[polymer]] [[elasticity (physics)|elasticity]], especially biopolymers such as [[RNA]] and [[DNA]].<ref>{{cite journal | vauthors = Williams MC, Rouzina I | title = Force spectroscopy of single DNA and RNA molecules | journal = Current Opinion in Structural Biology | volume = 12 | issue = 3 | pages = 330–336 | date = June 2002 | pmid = 12127451 | doi = 10.1016/S0959-440X(02)00340-8 }}</ref> Another [[biophysics|biophysical]] application of polymer force spectroscopy is on [[protein]] unfolding.<ref>{{cite journal | vauthors = Jagannathan B, Elms PJ, Bustamante C, Marqusee S | title = Direct observation of a force-induced switch in the anisotropic mechanical unfolding pathway of a protein | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 109 | issue = 44 | pages = 17820–17825 | date = October 2012 | pmid = 22949695 | pmc = 3497811 | doi = 10.1073/pnas.1201800109 | doi-access = free | bibcode = 2012PNAS..10917820J }}</ref> Modular proteins can be adsorbed to a [[gold]] or (more rarely) [[mica]] [[Interface (matter)|surface]] and then stretched. The sequential unfolding of modules is observed as a very characteristic sawtooth pattern of the force vs elongation graph; every tooth corresponds to the unfolding of a single protein module (apart from the last that is generally the detachment of the protein molecule from the tip). Much information about protein elasticity and protein unfolding can be obtained by this technique. Many proteins in the living [[cell (biology)|cell]] must face mechanical stress.

Moreover, force spectroscopy can be used to investigate the enzymatic activity of proteins involved in [[DNA replication]], [[Transcription (biology)|transcription]], organization and [[DNA repair|repair]]. This is achieved by measuring the position of a bead attached to a DNA-protein complex stalled on a DNA tether that has one end attached to a surface, while keeping the force constant. This technique has been used, for example, to study transcription elongation inhibition by Klebsidin and Acinetodin.<ref>{{cite journal | vauthors = Metelev M, Arseniev A, Bushin LB, Kuznedelov K, Artamonova TO, Kondratenko R, Khodorkovskii M, Seyedsayamdost MR, Severinov K | display-authors = 6 | title = Acinetodin and Klebsidin, RNA Polymerase Targeting Lasso Peptides Produced by Human Isolates of Acinetobacter gyllenbergii and Klebsiella pneumoniae | journal = ACS Chemical Biology | volume = 12 | issue = 3 | pages = 814–824 | date = March 2017 | pmid = 28106375 | doi = 10.1021/acschembio.6b01154 }}</ref>

The other main application of force spectroscopy is the study of [[mechanical resistance]] of chemical bonds. In this case, generally the tip is functionalized with a ligand that binds to another molecule bound to the surface. The tip is pushed on the surface, allowing for contact between the two molecules, and then retracted until the newly formed bond breaks up. The force at which the bond breaks up is measured. Since mechanical breaking is a kinetic, [[stochastic process]], the breaking force is not an absolute parameter, but it is a function of both temperature and pulling speed. Low temperatures and high pulling speeds correspond to higher breaking forces. By careful analysis of the breaking force at various pulling speeds, it is possible to map the [[energy]] landscape of the chemical bond under mechanical force.<ref>{{cite journal | vauthors = Merkel R, Nassoy P, Leung A, Ritchie K, Evans E | title = Energy landscapes of receptor-ligand bonds explored with dynamic force spectroscopy | journal = Nature | volume = 397 | issue = 6714 | pages = 50–53 | date = January 1999 | pmid = 9892352 | doi = 10.1038/16219 | s2cid = 4419330 | bibcode = 1999Natur.397...50M }}</ref> This is leading to interesting results in the study of [[antibody]]-[[antigen]], protein-protein, protein-living cell interaction and [[catch bonds]].<ref>{{cite journal | vauthors = Schoeler C, Malinowska KH, Bernardi RC, Milles LF, Jobst MA, Durner E, Ott W, Fried DB, Bayer EA, Schulten K, Gaub HE, Nash MA | display-authors = 6 | title = Ultrastable cellulosome-adhesion complex tightens under load | journal = Nature Communications | volume = 5 | issue = 1 | pages = 5635 | date = December 2014 | pmid = 25482395 | pmc = 4266597 | doi = 10.1038/ncomms6635 | bibcode = 2014NatCo...5.5635S }}</ref>

Recently this technique has been used in [[cell biology]] to measure the aggregative [[stochastic]] forces created by [[motor proteins]] that influence the motion of particles within the cytoplasm. In this way, force spectrum microscopy may be used better to understand the many cellular processes that require the motion of particles within cytoplasm.<ref>{{cite journal | vauthors = Guo M, Ehrlicher AJ, Jensen MH, Renz M, Moore JR, Goldman RD, Lippincott-Schwartz J, Mackintosh FC, Weitz DA | display-authors = 6 | title = Probing the stochastic, motor-driven properties of the cytoplasm using force spectrum microscopy | journal = Cell | volume = 158 | issue = 4 | pages = 822–832 | date = August 2014 | pmid = 25126787 | pmc = 4183065 | doi = 10.1016/j.cell.2014.06.051 }}</ref>