19F-Dehydrocoelenterazine as probe to investigate the active site of symplectin

Fluorinated dehydrocoelenterazines (F-DCTs) were synthesized to study molecular mechanisms of symplectin; a photoprotein of luminous squid Symplectoteuthis oualaniensis L. F-DCTs reacted with dithiothreitol and glutathione under neutral conditions to give the stable chromophores as symplectin model. Reconstructed symplectin was also obtained by addition of F-DCTs into apo-symplectin, and showed bioluminescence to emit 50–65% amount of light as natural symplectin. The structure of the chromophores was determined by 19F NMR, Q-TOF-MS, and MS/MS analyses. Sequencing of the chromopeptides of symplectin models prepared from F-DCTs and thiol compounds was accomplished by ESI-Q-TOF-MS/MS analysis.