. Author manuscript; available in PMC: 2022 Jul 6.

Published in final edited form as: Biochemistry. 2021 Jun 24;60(26):2130–2151. doi: 10.1021/acs.biochem.1c00246

Table 3.

Additivity of the effects of substitutions at various positions with A113P (K+4) on the autophosphorylation rate constant.

Substitutions	Expected value (ΔΔG^‡₁₊₂) ^a	Observed value (ΔΔG^‡) ^b	Absolute value of difference (\|Expected – Observed\|) ^c
CheY M17A A113P	1.01^d	1.02	0.01
CheY L24S A113P	1.53	0.85	0.68
CheY V86S A113P	1.13	0.18	0.95
CheY V108T A113P	1.01	0.98	0.03
CheY F111V A113P	2.08	1.25	0.83
CheY T112A A113P	1.15	1.20	0.05

The expected value, assuming no interaction between the individual positions, equals log₁₀(ratio of A113P to wild-type CheY rate constants) + log₁₀(ratio of specified single variant to wild-type CheY rate constants).

The actual value equals log₁₀(ratio of the specified double substitution to wild-type rate constants).

We considered a deviation from the anticipated additive effects significant if the absolute difference > 0.65, implying that one of the positions influences the contribution(s) of the other.

All table values are given in units of −RT.