k1 = k1 k2 = k2 k3 = k3 k4 = k4 k5 = k5 k6 = k6 k7 = k7 k8 = k8 k9 = k9 k10 = k10 k11 = cytosol k12 = NADPH k13 = O2 k14 = citrulline k15 = NO3 k16 = NO k17 = NADPplus k18 = __cm_k18