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Use of Agarose Gel Electrophoresis to Monitor Conformational Changes of Some Small, Spherical Plant Viruses. Louis A. Heaton, Assistant professor, Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan, KS 66506; Phytopathology 82:803-807. Accepted for publication 30 March 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-803.

Several small, spherical plant viruses undergo conformational changes (swell) under conditions that deprotonate carboxyl groups and/or remove divalent cations. In this study, swollen, ribonuclease A susceptible turnip crinkle carmovirus (TCV) and tomato bushy stunt tombusvirus (TBSV) particles migrated more slowly than contracted virions during agarose gel electrophoresis, and swollen TCV virions stained more intensely with ethidium bromide than did contracted virions. The swelling of TCV virions was prevented by the addition of 5.0 mM CaCl2 to alkaline treatments, whereas the addition of 5.0 mM MgCl2 did not prevent swelling. A portion of swollen TCV virions was contracted when the pH was shifted from 8.5 to 5.5. TBSV, which is more stable, expanded only in the presence of divalent cation chelators but not by alkaline treatments alone. Agarose gel electrophoresis is a quick, simple method that can be used to monitor pH- and chelator-induced conformational and permeability changes of some small, spherical plant viruses.