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. Author manuscript; available in PMC: 2016 Dec 15.
Published in final edited form as: Biochemistry. 2015 Dec 2;54(49):7248–7260. doi: 10.1021/acs.biochem.5b01082

Table 5.

Relative sensitivity of CheY variants for imidazole versus water

Receiver domain kdephos,imida (M−1s−1) kdephos,waterb ×10−5 (M−1s−1) Relative sensitivity to imidazolec
CheYMPI 4.3 ± 0.05 2.6 ± 0.3d 170,000
CheYSKN7 1.9 ± 0.4 3.9 ± 0.4d 48,000
CheYSLN1 8.2 ± 0.4 18.0 ± 4.2e 45,000
CheYsmall 1.2 ± 0.04 9.0 ± 0.6d 14,000
CheYSSK1 3.1 ± 0.1 34.0 ± 7.2e 9,000
CheYlarge 0.25± 0.005 3.3 ± 0.0f 8,200
CheYwt 1.1 ± 0.1 75.0 ± 9.0f 1,500
a

Values are averages of second order rate constants from 2–3 measurements (completed at pH 10.3) ± SD and are determined by pH-jump fluorescence except CheYMPI and CheYSKN7 were measured using 32P.

b

Calculated by dividing first order water-mediated dephosphorylation rate constants by the concentration of water (55.5 M). Multiply column values by 10−5.

c

Relative sensitivity was calculated by dividing kdephos,imid by kdephos,water.

d

First order water-mediated dephosphorylation rate constant determined using 32P as previously described in 22.

e

First order water-mediated dephosphorylation rate constant determined using pH-jump fluorescence described in 25.

f

First order water-mediated dephosphorylation rate constants from 22.