Table 1. Mutual influence of IF₁, efrapeptin, aurovertin B (I₁) and rhodamine 6G (I₂) on the binding of each other.

Values for the mutual influence factor, γ, were calculated by unweighted non-linear regression fits to eqn (1). Kinetic parameters derived from single inhibitor steady state kinetic experiments were assigned for the fits to eqn (1): IF₁ (K_EI=0.25 μM, α=0.72), efrapeptin (K_EI=0.12 μM, α=1.4), aurovertin B (α=0.05) and rhodamine 6G (K_EI=91 μM, α=0.29). K_EI represents the inhibition constant for the competitive component. Factor α represents the change in substrate affinity induced by inhibitor binding, or, alternatively, the alteration in the affinity for the inhibitor due to the bound substrate. The inhibition constant for the uncompetitive component K_ESI=αK_EI. A mean value of 370 μM was obtained for K_S. The K_EI value for aurovertin B could not be determined accurately, since the inhibition was predominantly uncompetitive and hence it was not included as a fixed parameter in the double inhibition non-linear regression fits to eqn (1). The data are expressed as the means±S.D.

Variable inhibitor	γ	Fold change in inhibition 1/γ
IF1	2.8±0.3	0.36
Efrapeptin	0.38±0.02	2.6
Aurovertin B	1.3±0.3	0.77