Diffusion Constant and Dimension of Bacteriophage φX174 as Determined by Self-Beat Laser Light Spectroscopy and Electron Microscopy

Abstract

The diffusion constant of bacteriophage φX174 was determined by laser light self-beat spectroscopy. The method allows one to establish the diffusion constant in comparatively short time and with high accuracy. From the diffusion constant D 37 = 1.96 ± 0.08 × 10 −7 cm 2 /s, the size of the virus particles within their aqueous milieu can be calculated. For φX174, a diffusional diameter of 31.4 ± 1.0 nm was found, in good agreement with measurements of diameters of freezeetched (32.3 ± 1.8 nm) and negatively stained particles (33.8 ± 2.1 nm), provided that the entire spikes of the virion are included. Other isometric viruses may show a complex interaction of the virion with the surrounding water and its ions.