Studies on luciferase from Photobacterium phosphoreum. XI. Interaction of 8-substituted FMNH2 with luciferase.
The interaction of bacterial luciferase from Photobacterium phosphoreum with reduced flavin was investigated using various 8-substituted FMNH2 analogs. Flavins tested were FMNH2 and FMNH2 substituted at the 8 position with HO-, CH3O-, C2H5O-, Cl-, Br-, I-, H2N-, (CH3)HN-, and (ch3)2n. 8-ch30-, c2h5o-, cl-, and Br-FMNH2 showed luminescent activity in the luciferase reaction with emission peaks at various wavelengths. 8-HO- and I-FMNH2 were competitive inhibitors toward FMNH2 in the luminescent reaction. 8-Amino analogs of FMNH2 showed no luminescent or inhibitor activity. The dissociation constant of the luciferase-FMNH2 analog complex was determined kinetically as a substrate or inhibitor constant. A contribution of the imino group at position 5 in the isoalloxazine ring to the FMNH2 binding to luciferase was suggested by a Hammett plot of the dissociation constants.
D005486:Flavin Mononucleotide / Q000031:analogs & derivatives*; D008156:Luciferases / Q000378:metabolism*; D008163:Luminescent Measurements; D010084:Oxidation-Reduction; D010776:Photobacterium / Q000201:enzymology*; D011485:Protein Binding; D013329:Structure-Activity Relationship
D005486:Flavin Mononucleotide; D008156:Luciferases