Sedimentation behavior of TreS in the absence and presence of Pep2.
(A) Sedimentation velocity analysis of TreS, Pep2, and molar mixtures
of the two as indicated on the right of the panel (absolute concentration
of TreS at 4.5 μM). With the exception of the trace in blue
(Pep2 alone, 9 μM), c(s) traces
have been spaced along the vertical axis according to the molar ratio
of [Pep2]/[TreS]. Arrows indicate the positions of the Pep2 monomer
and TreS tetramer, respectively. The dashed line highlights the shift
of the TreS tetramer peak in response to the addition of Pep2. (Inset)
Sedimentation coefficient of the TreS tetramer peak as a function
of the concentration ratio [Pep2]/[TreS]. (B) Sedimentation equilibrium
analysis of the TreS:Pep2 complex. Fit of a noninteracting species
model consisting of the TreS:Pep2 complex and free Pep2 (fixed at
52 kDa). TreS and Pep2 are at a concentration of 5 and 10 μM,
respectively. Rotation speeds are indicated. Equilibrium was allowed
to establish over a 24 h period at each speed, and several absorbance
scans were recorded per rotation speed, the last of each was used
in the data analysis.