Rate laws for the exchange of guanine nucleotides bound to EF-Tu catalysed by EF-Ts.

The rate laws governing the exchange of guanine nucleotides bound to EF-Tu catalysed by EF-Ts are set out and the information that is available from various studies is analysed in terms of the laws. In particular the consequences of k-1 being equal to k-4 in the reaction sequence as set out below are examined in relation to results obtained by Hwang and Miller (J. Biol. Chem. 260, 11498-11502) and the contradiction these pose in relation to other published results. Measurement of on and off rate constants for binding of GTP to EF-Tu.EF-Ts and of the affinity of EF-Ts for EF-Tu.GTP should prove of importance in resolving discrepancies.