Fig. 7.

XacAbf51 is a trimeric enzyme. a Comparison of TxAbfD3 hexamer with the molecules found in the asymmetric unit of XacAbf51 crystal (cartoon with transparent surface). The schemes highlight that in the XacAbf51 crystal structure the ABC and DEF trimers interact with each other in a different way compared to the trimer–trimer interface of TxAbfD3 hexamer. b SAXS curve (open circles) agrees with the theoretical profile of XacAbf51 trimer calculated from the crystal structure using CRYSOL. The inset shows the pair–distance distribution function computed from the experimental data and used to generate the low-resolution envelope (white surface) fitted to the crystallographic trimer (cartoon). c, d AUC data show that XacAbf51 assumes a trimer arrangement in a wide range of protein concentration. e Summary of size and mass parameters estimated using four biophysical techniques demonstrates that the quaternary structure of XacAbf51 is a trimer