Table 1.

The calculated results for the 2W mechanism and the corresponding observed values

System	∆g‡1	∆Gо1	∆g‡cal	∆g‡exp
Water	27.0	26.0	27.0	27.0*
EF-Tu′(wild)2W	14.4	12.8	13.8	<14.0†
EF-Tu′(H84NP)2W	17.0	16.1	17.1	—
EF-Tu′(H84A)2W	21.8	20.4	21.4	21.2†
EF-Tu′(H84Q)2W	18.7	17.5	18.5	∼18.4§
EF-Tu′(D21A)2W	18.6	17.3	18.3	18.4§
EF-G′(wild)2W	14.6	13.2	14.2	14.1¶
EF-G′(H87A)2W	25.0	23.7	24.7	>22#

∆g^‡₁ and ∆g^‡_cal are the calculated activation free energy for the nucleophilic attack step and the total reaction, respectively. ∆G^о₁ is the reaction free energy of the first step. ∆g^‡_exp is the activation free energy obtained from the experimentally determined rate of the hydrolysis. 2W denotes the two-water mechanism for GTP hydrolysis.

^*From ref. 33.

^†From ref. 1.

^§From ref. 21.

^¶From ref. 34.

^#From ref. 35.