TABLE 2.

Mammalian and E. coli E3 k_cat and flux optimization analysis

Calculations determining k_cat as a function of pH and optimization algorithms used to produce the flux maximum (J_max) are described in “Experimental Procedures.” Flux (J) optimizations required to produce J_max conserve NAD (54) and lipoamide (1) pool sizes of 3 and 10 mm, respectively.

Parameter	Mammalian E3a		E. coli E3b
	Forward	Reverse	Forward	Reverse
kcat(pH)c	2.6 × 105 (pH = 8.24)	369 (pH = 4)	2.1 × 104 (pH = 8)	9.5 (pH = 5.25)
Jmaxd	3.5 × 104	2 × 104	5.23 × 104	4.4 × 103
NAD+/NADHe	1012	10−12	9.6 × 1011	22
Lipo/DHLe	10−12	1012	10−12	22 × 1011
pH	9	5.6	8.11	7.67

^a Mammalian E3 k_cat (pH) and flux maximum (J_max) were determined using the 4-state redox K_d-dependent parameters shown in Table 1.

^b E. coli E3 k_cat (pH) and flux maximum (J_max) were determined using the previously described 3-state model and best-fit parameters (41).

^c Maximum k_cat (pH) values are displayed in units of min⁻¹.

^d E3 flux maximum (J_max) are displayed in units of min⁻¹.

^e NAD⁺/NADH and Lipo/DHL ratios were given a boundary between 10⁻¹² and 10¹² in this instance to allow for greater flux optimization compared with ratio values that were given tighter bounds that are more consistent with physiological conditions shown in Figs. 13 and 14.