"Cluster-ion" bombardment of biological macromolecules: Morphological evidence for disassembly of single tobacco mosaic virus particles.

Cluster ions containing 50, 100, or 200 water molecules and one proton are accelerated to over 275 kV and impacted on thin carbon films on which tobacco mosaic virus has been dispersed. After bombardment the films are examined with a transmission electron microscope to study induced morphological alterations with respect to the energy transfer processes that take place during and after single cluster-ion impact. Observations on tobacco mosaic virus indicate that a single cluster impact results in the removal of a cylindrical segment of the virus. No fragments from the excised TMV segment were observed on the carbon foil. We speculate that cluster-ion bombardment may become a useful analytical technique for structural studies of large biological macromolecular complexes.