Single Molecules
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| 1 | Dynamic strength of molecular adhesion bonds E. Evans, (evans@physics.ubc.ca )K. Ritchie, (kritchie@bio.nagoya-u.ac.jp ) Biophys. J. (1997-04-00) 72-4 p.1541 Biophyscal publications Publisher : BIOPHYSICAL SOCIETY, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3998 USA. ISSN : 0006-3495 Abstract : In biology, molecular linkages at, within, and beneath cell interfaces arise mainly from weak noncovalent interactions. These bonds will fail under any level of pulling force if held for sufficient time, Thus, when tested with ultrasensitive force probes, we expect cohesive material strength and strength of adhesion at interfaces to be time- and loading rate-dependent properties. To examine what can he learned from measurements of bond strength, we have extended Kramers' theory for reaction kinetics in liquids to bond dissociation under force and tested the predictions by smart Monte Carte (Brownian dynamics) simulations of bond rupture. By definition, bond strength is the force that produces the most frequent failure in repeated tests of breakage, i.e., the peak in the distribution of rupture forces. As verified by the simulations, theory shows that bond strength progresses through three dynamic regimes of loading rate. First, bond strength emerges at a critical rate of loading (greater than or equal to 0) at which spontaneous dissociation is just frequent enough to keep the distribution peak at zero force, In the slow-loading regime immediately above the critical rate, strength grows as a weak power of loading rate and reflects initial coupling of force to the bonding potential, At higher rates, there is crossover to a fast regime in which strength continues to increase as the logarithm of the loading rate over many decades independent of the type of attraction, Finally, at ultrafast loading rates approaching the domain of molecular dynamics simulations, the bonding potential is quickly overwhelmed by the rapidly increasing force, so that only naked frictional drag on the structure remains to retard separation, Hence, to expose the energy landscape that governs bond strength, molecular adhesion forces must be examined over an enormous span of time scales. However, a significant gap exists between the time domain of force measurements in the laboratory and the extremely fast scale of molecular motions. Using results from a simulation of biotin-avidin bonds (Izrailev, S., S. Stepaniants, M. Balsera, Y. Oono, and K. Schulten. 1997. Molecular dynamics study of unbinding of the avidin-biotin complex, Biophys. J., this issue), we describe how Brownian dynamics can help bridge the gap between molecular dynamics and probe tests. Corresponding Author : Evans, E, UNIV BRITISH COLUMBIA,DEPT PATHOL,6224 AGR RD,VANCOUVER,BC V6T 1Z1,CANADA. Affiliation(s) : (0) UNIV BRITISH COLUMBIA,DEPT PHYS,VANCOUVER,BC V6T 1Z1,CANADA.; Key words : ATOMIC FORCE MICROSCOPE; CELLS; DETACHMENT Type : Article, English. 1997-04-00 Time cited 347; Journal impact factor for year 1997 equals 4.332 [0] ALON R, 1995, NATURE, V374, P539 [1] ANSARI A, 1992, SCIENCE, V256, P1796 [2] ANSARI A, 1994, BIOCHEMISTRY-US, V33, P5128 [3] ASHKIN A, 1990, NATURE, V348, P346 [4] BATCHELOR GK, 1976, J FLUID MECH, V74, P1 [5] BELL GI, 1978, SCIENCE, V200, P618 [6] DEMBO M, 1988, P ROY SOC LOND B BIO, V234, P55 [7] EVANS E, 1991, BIOPHYS J, V59, P838 [8] EVANS E, 1994, STUDYING CELL ADHESI, P125 [9] EVANS E, 1995, BIOPHYS J, V68, P2580 [10] EVANS E, 1995, HDB PHYSICS BIOL SYS, V1, P7232 [11] FLORIN EL, 1994, SCIENCE, V264, P415 [12] GREEN NM, 1975, ADV PROTEIN CHEM, V29, P855 [13] GRUBMULLER H, 1996, SCIENCE, V271, P997 [14] HANGGI P, 1990, REV MOD PHYS, V62, P251 [15] HOH JH, 1992, J AM CHEM SOC, V114, P4917 [16] IZRAILEV S, 1997, BIOPHYS J, V72, P1568 [17] KRAMERS HA, 1940, PHYSICA, V7, P284 [18] KUO SC, 1993, SCIENCE, V260, P232 [19] LEE GU, 1994, LANGMUIR, V10, P354 [20] METROPOLIS N, 1953, J CHEM PHYS, V21, P1087 [21] MOY VT, 1994, SCIENCE, V266, P257 [22] RADMACHER M, 1992, SCIENCE, V257, P1900 [23] ROSSKY PJ, 1978, J CHEM PHYS, V69, P4628 [24] TEES DFJ, 1993, BIOPHYS J, V65, P1318 [25] WILLIAMS JM, 1996, LANGMUIR, V12, P1291 |
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