Table 3.

Specific enzyme parameters determined for the hydrolysis of pGpp, ppGpp, and pppGpp by Rel_Cg and RelH_Cg, respectively.

	RelCg			RelHCg
Substrate	Km [mM]	kcat [s-1]	kcat/Km [M-1 s-1]	Km [mM]	kcat [s-1]	kcat/Km [M-1 s-1]
pGpp	0.734 ± 0.127	0.794 ± 0.071	1.08 × 103	0.144∗	0.294∗	2.04 × 103
ppGpp	0.511 ± 0.01	0.296 ± 0.004	5.79 × 102	0.101 ± 0.007	0.502 ± 0.018	4.97 × 103
pppGpp	0.422∗	0.563∗	1.34 × 103	0.09 ± 0.011	0.09 ± 0.003	1.01 × 103

As a result of significant substrate inhibition, K_m and k_cat were calculated by linearized representation according to Eadie–Hofstee (Hofstee, 1959), using the lowest substrate concentrations (Supplementary Figures S2, S3). ^∗Due to the substrate inhibition, the parameters shown were only generated on the basis of two data points, which means that no error indication of the regression is possible.