Bacterial luciferase. Binding of oxidized flavin mononucleotide.

摘要: Bacterial luciferase catalyzes a bioluminescent oxidation of reduced flavin mononucleotide; the products include photon and oxidized FMN. The experiments reported here show that binds mononucleotide in 1:1 molar ratio with an apparent dissociation constant 1.2 times 10-4 M at 3 degrees 0.05 2,2-bis(hydroxymethyl)-2,2'2"-nitriloethanol (bis-tris), pH 7.0. Analysis binding temperatures between 30 indicates enthalpy (delta H a) minus 10.0 kcal per mol. absorption spectrum luciferase-bound FMN shows considerable alteration relative to free flavin. There is one major peak 366 nm, 445-nm band resolved into two distinct peaks 434 458 nm; this indicative nonpolar environment. circular dichroism bound has structure which correlates well optical detail spectra probably reflects resolution vibrational blurred polar environments. activity shown by CD presumably results from electronically asymmetric fashion. Although solution highly fluorescent, nonfluorescent, thus indicating emitting species not excited state product located same site