{beta}-connectin studies by small-angle x-ray scattering and single-molecule force spectroscopy by atomic force microscopy

Journal Article · Sun May 15 00:00:00 EDT 2011 · Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print)

DOI:https://doi.org/10.1103/PHYSREVE.83.051919· OSTI ID:21560285

Marchetti, S; Carla, M; Gambi, C M. C. ^[1]; Sbrana, F; Vassalli, M ^[2]; Toscano, A; Pacini, A ^[3]; Fratini, E ^[4]; Tiribilli, B ^[5]

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1. Department of Physics, University of Florence and CNISM Via G. Sansone 1, IT-50019, Sesto Fiorentino, Florence (Italy)
2. Biophysics Institute of the National Research Council, Via De Marini 6, Genova (Italy)
3. Department of Anatomy, Histology, and Forensic Medicine, University of Florence, Florence (Italy)
4. Department of Chemistry and Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), University of Florence, Via della Lastruccia 3, IT-50019, Sesto Fiorentino, Florence (Italy)
5. Complex System Institute of the National Research Council (ISC-CNR), Sesto Fiorentino, Florence (Italy)

The three-dimensional structure and the mechanical properties of a {beta}-connectin fragment from human cardiac muscle, belonging to the I band, from I{sub 27} to I{sub 34}, were investigated by small-angle x-ray scattering (SAXS) and single-molecule force spectroscopy (SMFS). This molecule presents an entropic elasticity behavior, associated to globular domain unfolding, that has been widely studied in the last 10 years. In addition, atomic force microscopy based SMFS experiments suggest that this molecule has an additional elastic regime, for low forces, probably associated to tertiary structure remodeling. From a structural point of view, this behavior is a mark of the fact that the eight domains in the I{sub 27}-I{sub 34} fragment are not independent and they organize in solution, assuming a well-defined three-dimensional structure. This hypothesis has been confirmed by SAXS scattering, both on a diluted and a concentrated sample. Two different models were used to fit the SAXS curves: one assuming a globular shape and one corresponding to an elongated conformation, both coupled with a Coulomb repulsion potential to take into account the protein-protein interaction. Due to the predominance of the structure factor, the effective shape of the protein in solution could not be clearly disclosed. By performing SMFS by atomic force microscopy, mechanical unfolding properties were investigated. Typical sawtooth profiles were obtained and the rupture force of each unfolding domain was estimated. By fitting a wormlike chain model to each peak of the sawtooth profile, the entropic elasticity of octamer was described.

• OSTI ID: 21560285
• Journal Information: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics (Print), Vol. 83, Issue 5; Other Information: DOI: 10.1103/PhysRevE.83.051919; (c) 2011 American Institute of Physics; ISSN 1539-3755
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMIC FORCE MICROSCOPY
COULOMB FIELD
ELASTICITY
HEART
HYPOTHESIS
INTERACTIONS
MOLECULES
MUSCLES
PLASMA INSTABILITY
PROTEINS
SAWTOOTH OSCILLATIONS
SMALL ANGLE SCATTERING
SPECTROSCOPY
STRUCTURE FACTORS
THREE-DIMENSIONAL CALCULATIONS
X-RAY DIFFRACTION
BODY
CARDIOVASCULAR SYSTEM
COHERENT SCATTERING
DIFFRACTION
DIMENSIONLESS NUMBERS
ELECTRIC FIELDS
INSTABILITY
MECHANICAL PROPERTIES
MICROSCOPY
ORGANIC COMPOUNDS
ORGANS
OSCILLATIONS
SCATTERING