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Purification and Composition of Potato Virus Y. R. Stace- Smith, Research Scientist, Canada Department of Agriculture, Research Station, 6660 N.W. Marine Drive, Vancouver 8, British Columbia, Canada; J. H. Tremaine, Research Scientist, Canada Department of Agriculture, Research Station, 6660 N.W. Marine Drive, Vancouver 8, British Columbia, Canada. Phytopathology 60:1785-1789. Accepted for publication 15 July 1970. DOI: 10.1094/Phyto-60-1785.

Potato virus Y (PVY) was purified from systemically infected leaves of Nicotiana tabacum ‘Haranova’. Of several procedures investigated for preliminary clarification of expressed sap, the most effective was alcohol or heat precipitation prior to differential centrifugation. A high molarity buffer to suspend the first high-speed pellet reduced to a minimum the aggregation of virus particles. The virus was further purified by sucrose-gradient centrifugation, where PVY sedimented as a single opalescent zone with a sedimentation coefficient of 150 S. The yield of purified virus was 3-4 mg/kg of leaves. The ultraviolet spectrum of the purified virus was typical of other tubular viruses, with absorption maximal at 260 nanometers (nm) and minimal at 247 nm. The purified virus had a phosphorus content of 0.49%, indicating a nucleic acid content of 5.4%. The amino-acid composition of the virus was similar to that of tobacco etch virus protein, another virus in the PVY group. The virus moved toward the anode in agar gel electrophoresis at pH 7.4.