The rotational diffusion coefficients of a small spherical particle, which is flexibly anchored to the surface of a much larger sphere, are calculated using the hydrodynamic theory of segmentally flexible particles. The model is intended for representing the rotational mobility of a small residue or chromophore in the surface of a globular macromolecule. The coefficients are found to be essentially independent, or to vary slowly with the relative dispositions of the spheres. They are also insensitive to the size ratio when this ratio is high enough. These findings support the use of an approximative treatment proposed by Wegener in which the small conformation dependence is averaged out. The resulting averages are tentatively used in the Lipari-Szabo model for restricted rotational diffusion in a cone. It is concluded that the rotational relaxation of the small sphere has three components: (i) a torsional rotation with the same diffusion coefficient as the free sphere; (ii) a perpendicular wobbling with a diffusion coefficient several (five in a typical case) times smaller; and (iii) an overall rotation of the whole macromolecule, that will appear in a much longer time scale if the two spheres have quite distinct sizes.
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Bloomfield VA (1985) Hydrodynamic properties of complex macromolecules. In: Bayley PM, Dale RE (eds) Spectroscopy and the dynamics of molecular biological systems. Academic Press, New York, pp 1–20
García de la Torre J (1981) Rotational diffusion coefficients. In: Krause S (ed) Molecular electro-optics. Plenum Press, New York, pp 75–103
García de la Torre J, Bloomfield VA (1981) Hydrodynamic properties of complex rigid, biological macromolecules: theory and applications. Q Rev Biophys 14:81–139
García de la Torre J, Rodes V (1983) Effects from bead size and hydrodynamic interactions on the translational and rotational friction coefficients of macromolecules bead models. J Chem Phys 83:2390–2397
García de la Torre J, Mellado P, Rodes V (1985) Diffusion coefficients of segmentally flexible macromolecules with two spherical subunits. Biopolymers 24:2145–2164
Goldstein RF (1985) Macromolecular diffusion constants: a calculational strategy. J Chem Phys 83:2390–2397
Gottlieb YY, Wahl P (1963) Etude theorique de la polarisation de fluorescence des macromolecules portant un groupe emetteur mobile autour d'un axe de rotation. J Chem Phys 60:849–856
Harvey SC (1979) Transport properties of particles with segmental flexibility. I. Hydrodynamic resistance and diffusion of a freely hinged particle. Biopolymers 18:1081–1104
Harvey SC, Cheung H (1980) Transport properties of particles with segmental flexibility. II. Decay of fluorescence polarization anisotropy from hinged macromolecules. Biopolymers 19:913–930
Harvey SC, Mellado P, García de la Torre J (1983) Hydrodynamic resistance and diffusion coefficients of segmentally flexible macromolecules with two subunits. J Chem Phys 78:2081–2090
Kinosita K Jr, Kawato S, Ikegami A (1977) A theory of fluorescence depolarization decay in membranes. Biophys J 20:289–304
Lipari G, Szabo A (1980) Effect of librational motion on fluorescence depolarization and nuclear magnetic resonance relaxation in macromolecules and membranes. Biophys J 30:489–506
Lipari G, Szabo A (1981) Padé approximants to correlation functions for restricted rotational diffusion. J Chem Phys 75:2971–2976
Reuland P, Felderhoff BU, Jones RB (1978) Hydrodynamic interaction of two spherically symmetric polymers. Physica A93:365–475
Szabo A (1984) Theory of fluorescence depolarization in macromolecules and membranes. J Chem Phys 81:150–167
Wegener WA (1980) The hydrodynamic resistance and diffusion coefficients of a freely hinged rod. Biopolymers 19:1899–1908
Wegener WA (1982a) A swivel-jointed formalism for segmentally flexible macromolecules and its application to the rotational behavior of myosin. Biopolymers 21:1039–1080
Wegener WA (1982b) Bead models of segmentally flexible macromolecules. J Chem Phys 76:6425–6430
Wegener WA, Dowben RA, Koester J (1980) Diffusion coefficients of segmentally flexible macromolecules: general formalism and application to rotational behavior of a body with two segment. J Chem Phys 73:4086–4097
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Iniesta, A., García de la Torre Rotational diffusion coefficients of a small, spherical subunit flexibly tethered to a larger sphere. Eur Biophys J 14, 493–498 (1987). https://doi.org/10.1007/BF00293259
- Rotational diffusion
- tethered sphere
- anisotropy decay
- segmental flexibility