Force-clamp spectroscopy with a small dithering of AFM tip, and its application to explore the energy landscape of single avidin-biotin complex.
We have recently developed a new method for directly measuring the spring constant of single molecules and molecular complexes on a real-time basis [L.A. Chtcheglova, G.T. Shubeita, S.K. Sekatskii, G. Dietler, Biophys. J. 86 (2004) 1177]. The technique combines standard force spectroscopy with a small dithering of tip. Changes in the amplitude of the oscillations are measured as a function of the pulling-off force to yield the spring constant of the complex. In this report, we present the first results of combination of this approach with the force-clamp spectroscopy. The standard atomic-force microscope has been supplemented with an electronic unit, which is capable of realizing an arbitrary force function, and permits the force-loading regime to be interrupted at any time. Using this method, the time needed to rupture a single bond can be measured as a function of the force that is required to maintain the complex in a stretched condition. The energy landscape of the avidin-biotin complex is explored and discussed.
Favre
M
M
Laboratoire de Physique de la Matière Vivante, IPMC, BSP, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Chtcheglova
L A
LA
Lapshin
D A
DA
Sekatskii
S K
SK
Valle
F
F
Dietler
G
G
D001360:Avidin / Q000737:chemistry*; D001710:Biotin / Q000737:chemistry*; D018625:Microscopy, Atomic Force / Q000379:methods*; D013057:Spectrum Analysis
D001360:Avidin; D001710:Biotin