FIG 3.

Effect of modifications on theoretical capsid pI. Box and whisker plots represent the range of empirical pIs found in the literature, while circles represent predicted pIs. The predicted pIs reflect the theoretical capsid charges: without modification, after excluding known viral polynucleotide-binding regions (“PBRs removed”) and after removing capsid interior surfaces using 3D structures [“Interior surface removed (3-D)”]. Both modifications were not possible for some viruses due to unknown PBR locations, unavailable 3D structures, and/or large size. A key to the 23 virus abbreviations (x axis) is provided in Table 2.