Direct Detection of Inter‐residue Hydrogen Bonds in Polysaccharides by Single‐Molecule Force Spectroscopy

Zhang, Qingmin; Jaroniec, Justyna; Lee, Gwangrog; Marszałek, Piotr E.

doi:10.1002/anie.200462067

Cited by 38 publications

(52 citation statements)

References 64 publications

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“…Such simulations established that the amylose extension per glucose ring at a force of 3270 pN is 5.57 Å, and this length is independent of the solvent. 18 To normalize the experimental force curves, therefore, we assume that the extension of these chains "per ring" is at 3270 pN equal to 5.57 Å. To normalize force curves that did not reach 3270 pN, we simply used the curves that reached 3270 pN as templates to give the "correct" lengths at lower forces.…”

Section: Normalization Of Force Spectrogramsmentioning

confidence: 99%

“…For example, this type of molecular manipulation has already enabled direct measurement of intramolecular hydrogen bonds in amylose that had been pulled into the poor solvent dimethyl carbonate. 18 Here, we use AFM-based single-molecule force spectroscopy to pull individual amylose molecules into aqueous iodine solution and into butanol to directly probe the relationship between their mechanical properties and their secondary structure in these solvents. We corroborate our results by steered molecular dynamics simulations of amylose in explicit butanol.…”

Section: Introductionmentioning

confidence: 99%

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Direct Detection of the Formation of V-Amylose Helix by Single Molecule Force Spectroscopy

Zhang

et al. 2006

J. Am. Chem. Soc.

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An important polysaccharide, amylose crystallizes as a regular single left-handed helix from a propanol, butanol or iodine solution. However, its solution structure remains elusive because amylose does not form molecular solutions in these solvents, and standard spectroscopic techniques cannot be exploited to determine its structure. Using the AFM, we forced individual amylose chains adsorbed to a surface to enter these poor solvents and carried out stretch-release measurements on them in solution. In this way, we directly captured the formation of individual amylose helices induced by butanol and iodine. With an accuracy approaching that of X-ray diffraction on amylose crystals, we determined that the pitch of the helix in solution is 1.3 Å/ring. We also directly measured the force driving the formation of the helix in solution to be 50 pN. SMD simulations in explicit butanol reproduced the AFM-measured force-extension curves and revealed that the long plateau feature is caused by the rupture of O(2) n -O(6) n+6 and O(3) n -O(6) n+6 hydrogen bonds and by the unwinding of the helix. We also found that amylose helices formed in iodine solution are more compliant and hysteretic as compared to helices in butanol, which extend/relax reversibly. In iodine solution, the formation of the helix is inhibited by force and limited by the slow kinetics of the amylose-iodine complex. By forcing individual molecules into poor solvents and performing force spectroscopy measurements in solution, our AFM approach uniquely supplements X-ray diffraction and NMR methods for investigating solution conformations of insoluble biopolymers.

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Section: Normalization Of Force Spectrogramsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Direct Detection of the Formation of V-Amylose Helix by Single Molecule Force Spectroscopy

Zhang

et al. 2006

J. Am. Chem. Soc.

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“…Thus, by assuming that the extension of a polysaccharide chain, at a given force that is common to all the recordings, is equal to one, we can eliminate the dependence of the shape of the force curve on the particular value of the contour length. Details are available in our previous papers [1,6]. In addition, for these polysaccharides for which we carried out SMD simulations we can use the SMD results to normalize the chain extension with respect to a single sugar ring.…”

Section: Normalization Of Force-extension Curvesmentioning

confidence: 99%

“…SMD simulations [1,3,4,6] of amylose, pustlan and dextran and data analysis were carried out with the programs NAMD2 [16], XPLOR [17], VMD [18] and a new CHARMM-based carbohydrate solution force field [19]. Briefly, AFM stretching measurements on individual polymers are modeled in the SMD protocol by fixing one terminal of the polymer and applying an external harmonic potential to the other terminal.…”

Section: Steered Molecular Dynamic Simulationsmentioning

confidence: 99%

“…These types of stretching measurements of polymers evolved into single-molecule force spectroscopy, which examines the relationship between a polymer length (end-to-end distance) and tension. Among biopolymers studied with the use of AFM-based single-molecule force spectroscopy, polysaccharides revealed a particular wealth of conformational behaviors that could be controlled by external forces [1][2][3][4][5][6][7][8][9][10][11]. For example, AFM stretching measurements captured forced chair-to-boat transitions of the pyranose ring in a-1,4 and a-1,6-linked glucose-based polysaccharides such as amylose, and dextran [2,4,7,12], chair-to-inverted chair transitions of a-Dgalactose in such polysaccharides as pectin [8] and l-carrageenan [10,11] and forced rotations around the C5-C6 bond of D-glucose in b-1,6-linked pustulan [3].…”

Section: Introductionmentioning

confidence: 99%

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