binding of FMN by apoenzyme is noncooperative, exothermic and primarily enthalpy driven with significant conformational changes in enzyme upon binding. The kinetically deduced ping-pong mechanism is supported by measurement of binding affinities of the oxidized and reduced FMN cofoactors
single-enzyme kinetic assay, SsuE follows ordered sequential mechanism with NADPH as the first substrate to bind and NADP+ as the last product to leave. In presence of monooxygenase SsuD and octanesulfonate mechanism is altered to rapid equilibrium ordered mechanism, and Km-value for FMN increases 10fold
the nicotinamide of NAD+ stacks the isoalloxazine ring of FMN so that NADH can directly transfer hydride. The bound NADP+ also has a compact conformation but is bound in a reverse direction, which is not suitable for hydride transfer
the enzyme catalysis obeys the ping-pong Bi-Bi kinetic mechanism with substrate FMN as well as substrate nitrofurazone, but upon coupling with the bioluminescent reaction of luciferase, it changes to the sequential mechanism
the nicotinamide of NAD+ stacks the isoalloxazine ring of FMN so that NADH can directly transfer hydride. The bound NADP+ also has a compact conformation but is bound in a reverse direction, which is not suitable for hydride transfer
the enzyme catalysis obeys the ping-pong Bi-Bi kinetic mechanism with substrate FMN as well as substrate nitrofurazone, but upon coupling with the bioluminescent reaction of luciferase, it changes to the sequential mechanism