FLEXIBILITY OF BACTERIOPHAGE-M13 - COMPARISON OF HYDRODYNAMIC MEASUREMENTS WITH ELECTRON-MICROSCOPY

The flexibility of the virus M13 has been investigated in solution and by electron microscopy. The rotational and translational diffusion coefficients have been determined by transient electric birefringence and analytical ultracentrifugation to DRf = 21.4 sec-1 and DTf = 2.34 × 10-8 cm2 sec-1, respectively. These data are interpreted in terms of a rigid rod or a weakly bending rod model. For a virus length of 915 nm evaluated by electron microscopy a weak but finite flexibility results. Our data are consistent with those reported for the closely related fd virus. Rotary shadowing electron microscopy has been applied using either the spraying or the sandwich technique. The observed flexibility parameter λL of the virus depends crucially on the preparation. A comparison with the hydrodynamic values shows that the sandwich technique (γL ≥ 0.1) reflects the flexibility of the virus in solution much better than the spraying technique (γL ≥ 0.5) which might be due to differences in the adsorption process. © 1990.