[33] Cypridina luciferin and luciferase

Chemi- and Bioluminescence of Cyclic Peroxides

Bioluminescence is a phenomenon that has fascinated mankind for centuries. Today the phenomenon and its sibling, chemiluminescence, have impacted society with a number of useful applications in fields like analytical chemistry and medicine, just to mention two. In this review, a molecular-orbital perspective is adopted to explain the chemistry behind chemiexcitation in both chemi- and bioluminescence. First, the uncatalyzed thermal dissociation of 1,2-dioxetane is presented and analyzed to explain, for example, the preference for triplet excited product states and increased yield with larger nonreactive substituents. The catalyzed fragmentation reaction and related details are then exemplified with substituted 1,2-dioxetanone species. In particular, the preference for singlet excited product states in that case is explained. The review also examines the diversity of specific solutions both in Nature and in artificial systems and the difficulties in identifying the emitting species and unraveling the color modulation process. The related subject of excited-state chemistry without light absorption is finally discussed. The content of this review should be an inspiration to human design of new molecular systems expressing unique light-emitting properties. An appendix describing the state-of-the-art experimental and theoretical methods used to study the phenomena serves as a complement.

Perfusion-culture-based secreted bioluminescence reporter assay in living cells

Bioluminescence reporter proteins have been widely used in the development of tools for monitoring biological events in living cells. In this study, we describe the development of a reporter system with secreted Cypridina noctiluca luciferase (CLuc) for a pharmacological assay that is based on targeted promoter activity. A model cell line was established with Rat-1 fibroblasts expressing CLuc driven by the promoter of a circadian clock gene, Bmal1. To accurately assay for temporally secreted CLuc activity, a perfusion culture in which the promoter activity was sequentially monitored by the reporter activity in the perfusate was adopted. By pulsing with dexamethasone (DEX), a glucocorticoid (GC) analog, the profile of the reporter activity successfully showed diurnal fluctuation, which is a canonical expression pattern of the Bmal1 gene. Trial studies illustrated that the DEX-pulsed circadian oscillation was reasonably attenuated by RU486, a GC receptor antagonist. Moreover, SP600125, a c-Jun N-terminal kinase inhibitor, caused phase shifting of the rhythmicity. We conclude that the CLuc reporter assay in combination with perfusion culture is a suitable pharmacological tool for drug discovery.