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. 2021 Sep 16;28(9):1333–1346.e7. doi: 10.1016/j.chembiol.2021.03.001

Table 2.

Activation and kinetics of IslA variants from reactions repeated in triplicate

Protein Percentage of active sites containing glycyl radical (%) Detectable activity (sulfite) KM (mM) kcat (s−1) Glycyl radical normalized kcat (s−1) Catalytic efficiency using normalized kcat (s−1 M−1)
Wild-type 20.8 ± 0.5 yes 8 ± 2 2.0 ± 0.1 9.5 ± 0.6 1200 ± 310
G805A 0 no N/D N/D N/D
C468S 22.1 ± 0.4 no N/D N/D N/D
E470Q 11.2 ± 0.7 no N/D N/D N/D
Q193A 17 ± 1 no N/D N/D N/D
R189E 28.1 ± 0.6 no N/D N/D N/D
R678E 5.9 ± 0.1 no N/D N/D N/D
R189E/R678E 11 ± 1 no N/D N/D N/D
F682A 11 ± 1 yes 6.8 ± 0.6 0.0171 ± 0.0004 0.154 ± 0.004 23 ± 2.1
F682Y 32.2 ± 0.8 yes 8 ± 1 0.0074 ± 0.0003 0.023 ± 0.001 2.9 ± 0.4
W374F 47 ± 2 yes 11 ± 1 0.063 ± 0.003 0.133 ± 0.006 12 ± 1.2
W374Y 30.2 ± 0.9 yes 16.0 ± 0.9 0.140 ± 0.003 0.465 ± 0.009 29 ± 1.7
I192A 21 ± 1 yes 12 ± 2 0.40 ± 0.02 1.9 ± 0.1 160 ± 28
V680A 52 ± 3 no N/D N/D N/D

Percentage of active sites containing glycyl radical indicate mean ± standard deviations; kinetic parameters are listed as mean ± standard error. N/D, not determined