Fig. 7. Binding of K346 to MTs.

K346 was added to a gently stirred suspension of MTs and the turbidity increase was determined by the difference in absorbance at 320 nm between before and immediately after addition of K346. A small correction was applied for the turbidity of K346 in the absence of MTs. The MT concentration was 0.8 μM (indicated by the vertical line) after correction for depolymerized tubulin that remained in the supernatant after ultracentrifugation to remove MTs. Apo-K346 as E^A in stabilization buffer into buffer with 1 mM ADP (diamonds) or without ADP (circles), apo-K346 as E^R without glycerol into buffer without ADP (triangles). The fitted curves were calculated using a mutual depletion scheme and assuming that the MT complex of E^R has the same maximum turbidity value as observed for E^A.