Computational analysis of the oxygen addition at the C4a site of reduced flavin in the bacterial luciferase bioluminescence reaction.
The energetic characteristics of selected reaction steps in the bacterial luciferase-catalyzed luminescence reaction were examined by computation using the MNDO-PM3 method. Specifically, a three-step model was proposed to account for the reaction between oxygen and reduced riboflavin 5'-phosphate (1,5H2-FMN) to generate first the 5-hydroFMN-4a-peroxide (5H-FMN-4aOO-) and then the 5-hydro-4a-hydroperoxyFMN (5H-FMN-4aOOH) intermediates. Lysine (Lys-H+) and aspartate (Asp-) were chosen as representative catalytic residues involved in the protonation and deprotonation processes. Results show that deprotonation at the N1 site of 1,5H2-FMN by a basic amino acid residue at the luciferase active site would efficiently accelerate the reaction rate of O2 addition to form 5H-FMN-4aOO-. The most favored site of oxygen attack is at the flavin C4a. With the aid of a catalytic acid group, the 5H-FMN-4aOO- so formed tends to undergo a spontaneous protonation reaction to yield the 5H-FMN-4aOOH.
Department of General Education Physics, Toyo University, Kawagoe, Japan. bhwada@eng.toyo.ac.jp
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D001419:Bacteria / Q000201:enzymology; D005415:Flavins / Q000737:chemistry / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism*; D049449:Luminescence; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D013816:Thermodynamics
D005415:Flavins; D008156:Luciferases; D010100:Oxygen