FIGURE 2.
EF-Tu is highly active in both the absence and presence of EF-Ts. The fraction of active EF-Tu molecules present in our protein preparation was determined by titrating EF-Tu (open squares) or EF-Tu·EF-Ts (closed diamonds) into a solution of 400 nm Phe-tRNAPhe (Cy3-acp3U47) in the presence of 10 μm GTP. Linear fits of the initial and final 10 data points of these two experiments intercept at 517 and 496 nm for EF-Tu and EF-Tu·EF-Ts, respectively, indicating that EF-Tu is ∼80% active in the absence and presence of EF-Ts.