Reciprocal plots demonstrating the linear, uncompetitive inhibition with respect to MgATP by free biotin for the bicarbonate-dependent ATPase reaction catalyzed by the R353M/K1119Q RePC double mutant. Solid lines indicate the least-square fits to eqn (3) at varying concentrations of MgATP (0.09–3.0 mM) and fixed concentrations of biotin (0 mM, black; 1 mM, red; 3 mM, blue; 5 mM, green; 7 mM, pink; 10 mM, cyan).