FIGURE 3.

Intersubunit interactions. A, size exclusion column analyses for the WT and R227E mutant of Tk-R15Pi. The molecular masses were calculated to be 260 and 140 kDa, respectively. The mass for WT was slightly larger than that of the calculated mass (217 kDa) of the hexamer from the amino acid sequence, probably because the shape of the Tk-R15Pi hexamer was oval. B, additional β-strand (β8(B)) for the Rossmann fold-like conformation and salt bridges in the dimerization surface. C, contacts of Tyr³⁰⁰ around the non-crystallographic 3-fold axis. D, intersubunit salt bridges by Arg²²⁷, which are responsible for the hexamerization.