Postprint version. Published in Biophysical Journal, Volume 46, Issue 1, July 1, 1984, pages 57-64. Copyright © 1984 Elsevier. The definitive version is available at http://dx.doi.org/10.1016/S0006-3495(84)83998-3.
NOTE: At the time of publication, the author Richard B. Frankel was not yet affiliated with Cal Poly.
Diffusive motions of the magnetosomes (enveloped Fe3O4 particles) in the magnetotactic bacterium Aquaspirillum magnetotacticum result in a very broad-line Mössbauer spectrum (T ~ 100 mm/s) above freezing temperatures. The line width increases with increasing temperature. The data are analyzed using a bounded diffusion model to yield the rotational and translational motions of the magnetosomes as well as the effective viscosity of the material surrounding the magnetosomes. The results are <θ2>l/2 < 1.5° and <x2>1/2 < 8.4 Å for the rotational and translational motions, respectively, implying that the particles are fixed in whole cells. The effective viscosity is 10 cP at 295 K and increases with decreasing temperature. Additional Fe3+ material in the cell is shown to be associated with the magnetosomes. Fe2+ material in the cell appears to be associated with the cell envelope.