DRAMATIC CAPACITY. “The versatility of the HK97-fold is also evident when comparing the diameters of capsids with confirmed HK97-like coat proteins, which range from ~24 nm to ~185 nm. This fold evolved to accommodate these dramatic differences in capsid diameter and the varying degrees of capsid curvature accompanying the spectrum of diameters.”
http://www.sciencedirect.com/science/article/pii/S0042682215001920