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. 2009 May 6;284(28):18651–18663. doi: 10.1074/jbc.M109.004267

TABLE 3.

Parameters characterizing the energy barriers (xu, k0, and ΔG‡) and spring constants (κ) of stable structural segments of SteT

Parameters are shown for the outer (substrate-freeouter) and inner (substrate-freeinner) barrier of substrate-free SteT and SteT in the presence of 5 mm l-serine or 5 mm l-threonine. Errors represent S.D. Changes in transition state, xu, were considered significant when the values for xu ± 2 S.D. did not overlap. Changes in transition rate, k0, were considered significant when exceeding 2 orders of magnitude. Barrier heights, ΔG‡, and spring constants, κ, were calculated as described under “Experimental Procedures.” pos., position. Values in bold changed by more than 3 orders of magnitude.

Peak pos. xu ± S.D.
 k0 ± S.D.
Substrate-freeouter Substrate-freeinner l-Serine l-Threonine Substrate-freeouter Substrate-freeinner l-Serine l-Threonine
aa nm s−1
70 2.71 ± 2.85 0.23 ± 0.03 0.57 ± 0.05 1.10 ± 0.22 1.4 ± 78 × 10−19 15.5 ± 9 0.031 ± 0.030 1.5 ± 6.4 × 10−6
79 4.65 ± 14.5 0.29 ± 0.07 0.42 ± 0.04 0.57 ± 0.07 4.4 ± 1400 × 10−42 2.2 ± 3.7 0.043 ± 0.040 1.6 ± 2.7 × 10−3
147 2.68 ± 1.82 0.36 ± 0.03 0.59 ± 0.05 0.67 ± 0.05 1.8 ± 39 × 10−11 6.7 ± 2.4 0.14 ± 0.09 0.078 ± 0.049
192 0.74 ± 0.10 0.21 ± 0.02 0.38 ± 0.02 0.55 ± 0.06 7.7 ± 7.4 × 10−2 26.7 ± 8.0 1.6 ± 0.4 0.17 ± 0.14
237 2.15 ± 0.98 0.27 ± 0.04 0.69 ± 0.07 1.34 ± 0.26 7.3 ± 82 × 10−9 15.0 ± 6.5 0.040 ± 0.034 8.7 ± 31 × 10−6
302 2.58 ± 1.19 0.24 ± 0.03 0.69 ± 0.06 0.79 ± 0.09 1.0 ± 16 × 10−12 12.2 ± 4.2 0.011 ± 0.010 3.7 ± 4.9 × 10−3
422 4.98 ± 4.58 0.30 ± 0.05 1.34 ± 0.21 0.83 ± 0.07 1.4 ± 110 × 10−34 3.3 ± 2.3 2.3 ± 8.5 × 10−8 1.4 ± 1.9 × 10−4
Peak pos. ΔG‡
 κ
Substrate-freeouter Substrate-freeinner l-Serine l-Threonine Substrate-freeouter Substrate-freeinner l-Serine l-Threonine
aa kBT N/m
70 62 16 22 32 0.07 2.41 0.55 0.22
79 114 18 22 25 0.04 1.72 1.00 0.64
147 43 17 21 21 0.05 1.06 0.49 0.39
192 21 15 18 20 0.32 2.84 1.01 0.55
237 37 16 22 30 0.07 1.84 0.38 0.14
302 46 16 23 24 0.06 2.27 0.40 0.32
422 97 17 36 27 0.03 1.64 0.17 0.33