Cross-linking of the Subunits of Potato Virus X with Di-imidates

The protein subunits of the X^N strain of potato virus X (PVX) were cross-linked by di-imidates to produce a series of polymers in the proportion expected from the random cross-linking of subunits in an extensive heterologous array. Polymerization of the subunits of chemically modified forms of the virus, as well as of other strains, suggests that the cross-links are heterogeneous, and may, but need not, involve the two amino groups that have been previously characterized as either reacting with chlorogenoquinone or being sensitive to trypsin.