The Study of Molecular Interactions by AFM Force Spectroscopy

Hugel, Thorsten; Seitz, Markus

doi:10.1002/1521-3927(20010901)22:13<989::aid-marc989>3.0.co;2-d

Cited by 339 publications

(378 citation statements)

References 89 publications

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“…[6][7][8] In our previous work, 9 we applied force spectroscopy to measure the interaction force between chitin and two different kinds of chitin-binding domains (ChBDs) of a multidomain chitinase. The chitinase is produced by Thermococcus kodakarensis KOD1, a hyperthermophilic archaeon, and is composed of five characteristic domains, including dual catalytic domains (CatD A and B) and triple ChBDs (ChBD1, ChBD2 and ChBD3).…”

Section: Introductionmentioning

confidence: 99%

Binding ability of chitinase onto cellulose: an atomic force microscopy study

Kikkawa

Fukuda

Kashiwada

et al. 2011

Polym J

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Section: Introductionmentioning

confidence: 99%

Binding ability of chitinase onto cellulose: an atomic force microscopy study

Kikkawa

Fukuda

Kashiwada

et al. 2011

Polym J

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“…However, one of the emerging research areas in soft-condensed matter physics is the manipulation of individual polymer chains by atomic force microscopy, magnetic levitation force microscopy, photonic force microscopy, and by using optical tweezers and the surface force apparatus. [7][8][9][10][11][12] Using these methods it is possible to measure the elasticity of materials at the molecular level. This exciting possibility gives an impulse to the new and expanding field of nanomechanics.…”

Section: Introductionmentioning

confidence: 99%

Negative compressibility and nonequivalence of two statistical ensembles in the escape transition of a polymer chain

Skvortsov

Klushin

Leermakers

2007

The Journal of Chemical Physics

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An end-tethered polymer chain compressed between two pistons undergoes an abrupt transition from a confined coil state to an inhomogeneous flowerlike conformation partially escaped from the gap. This phase transition is first order in the thermodynamic limit of infinitely long chains. A rigorous analytical theory is presented for a Gaussian chain in two ensembles: ͑a͒ the H-ensemble, in which the distance H between the pistons plays the role of the independent control parameter, and ͑b͒ the conjugate f-ensemble, in which the external compression force f is the independent parameter. Details about the metastable chain configurations are analyzed by introducing the Landau free energy as a function of the chain stretching order parameter. The binodal and spinodal lines, as well as the barrier heights between the stable and metastable states in the free energy landscape, are presented in both ensembles. In the loop region for the average force with dependence on the distance H ͑i.e., in the H-ensemble͒ a negative compressibility exists, whereas in the f-ensemble the average distance as a function of the force is strictly monotonic. The average fraction of imprisoned segments and the lateral force, taken as functions of the distance H or the average H, respectively, have different behaviors in the two ensembles. These results demonstrate a clear counterexample of a main principle of statistical mechanics, stating that all ensembles are equivalent in the thermodynamic limit. The authors show that the negative compressibility in the escape transition is a purely equilibrium result and analyze in detail the origin of the nonequivalence of the ensembles. It is argued that it should be possible to employ the escape transition and its anomalous behavior in macroscopically homogeneous, but microscopically inhomogeneous, materials.

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“…Our experiments enhance the ability of single-molecule force spectroscopy to make high-resolution measurements of the conformations of single polysaccharide molecules under a stretching force, making an important addition to polysaccharide spectroscopy. S ingle molecule force spectroscopy has become an important tool to examine the conformations of proteins and polysaccharide molecules under a stretching force (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Recent experiments have demonstrated that a force field can trigger conformational changes in these molecules that cannot be observed by traditional NMR or x-ray crystallographic techniques.…”

mentioning

confidence: 99%

Chair-boat transitions in single polysaccharide molecules observed with force-ramp AFM

Marszałek

Oberhauser

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

136

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Under a stretching force, the sugar ring of polysaccharide molecules switches from the chair to the boat-like or inverted chair conformation. This conformational change can be observed by stretching single polysaccharide molecules with an atomic force microscope. In those early experiments, the molecules were stretched at a constant rate while the resulting force changed over wide ranges. However, because the rings undergo force-dependent transitions, an experimental arrangement where the force is the free variable introduces an undesirable level of complexity in the results. Here we demonstrate the use of force-ramp atomic force microscopy to capture the conformational changes in single polysaccharide molecules. Force-ramp atomic force microscopy readily captures the ring transitions under conditions where the entropic elasticity of the molecule is separated from its conformational transitions, enabling a quantitative analysis of the data with a simple two-state model. This analysis directly provides the physico-chemical characteristics of the ring transitions such as the width of the energy barrier, the relative energy of the conformers, and their enthalpic elasticity. Our experiments enhance the ability of single-molecule force spectroscopy to make high-resolution measurements of the conformations of single polysaccharide molecules under a stretching force, making an important addition to polysaccharide spectroscopy. S ingle molecule force spectroscopy has become an important tool to examine the conformations of proteins and polysaccharide molecules under a stretching force (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Recent experiments have demonstrated that a force field can trigger conformational changes in these molecules that cannot be observed by traditional NMR or x-ray crystallographic techniques. Force spectroscopy involves measuring the force required to extend a molecule by a certain amount (2-10). The data are compiled into a forceextension relationship that gives a characteristic fingerprint for the conformational transitions of the molecule under study. For example, force-extension relationships of polysaccharides such as amylose and dextran (13, 14) display a characteristic plateau (2, 4) that marks forced transitions of the glucose monomers from their chair conformation to the boat-like conformation (4). Similarly, two distinct plateaus in the force-extension curve of pectin (13, 14) report a transition of the galactose rings from the chair conformation to the boat conformation and a subsequent flip of the boat to the inverted chair conformation (5). These observations provide an interesting perspective on the behavior of polysaccharides under mechanical tension (15) and suggest that fingerprints of forced conformational transitions can be used as a means for identifying single polysaccharides molecules in solution (9).In the most typical atomic force microscopy (AFM) experiment, a single molecule adsorbed between a substrate and the cantilever tip is extended vertically at a constant rate while t...

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The Study of Molecular Interactions by AFM Force Spectroscopy

Cited by 339 publications

References 89 publications

Binding ability of chitinase onto cellulose: an atomic force microscopy study

Binding ability of chitinase onto cellulose: an atomic force microscopy study

Negative compressibility and nonequivalence of two statistical ensembles in the escape transition of a polymer chain

Chair-boat transitions in single polysaccharide molecules observed with force-ramp AFM

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