Biochemical species luminescence

Despite the relatively common occurrence of luminous echino-derms, only two species of ophiuroid, Ophiopsila califomica and Amphiura filiformis, have been biochemically investigated. It is surprising that the former species luminesces with a photoprotein system, whereas the latter emits light with a luciferin-luciferase system. 

Colepicolo-Neto, P., Costa, C., and Bechara, E. J. H. (1986). Brazilian species of luminescent Elateridae. Luciferin identification and bioluminescence spectra. Insect Biochem. 16 803-810. 

Johnston, T. C., et al. (1990). The nucleotide sequence of the luxA and luxB genes of Xenorhabdus luminescence HM and a comparison of the amino acid sequences of luciferases from four species of bioluminescent bacteria. Biochem. Biophys. Res. Commun. 170 407- 115. 

Fukada, H., A. Haga, T. Fujita, N. Hiramatsu, C.V. Sullivan and A. Hara. Development and validation of chemi-luminescent immunoassay for vitellogenin in five salmonid species. Comp. Biochem. Physiol. 130A 163-170, 2001. 

Dewael Y, Mallefet J. Calcium involvement in the luminescence control of three ophiuroid species (Echinodermata). Comp Biochem Physiol C 2002 131 153-60. 

The behavior of this Ru(II)-Cr(III) chromophore-Iuminophore complex (as well as of some related ones [69]) provides an example of how the properties of a luminophore can be improved by attachment to a suitable chromophoric component (spectral sensitization, antenna effect, avoidance of possible quartet photoprocesses). When very specific light absorption and light emission characteristics are required (e.g., in the design of luminescent labels for biochemical applications), the use of chromophore-Iuminophore systems may represent a convenient strategy. In particular this strategy permits separate optimization of absorption and emission properties, a possibility which is precluded in simple molecular species. 

Multi-exponential decays can also be observed from a single luminescent compound. For example, the compound under examination can be present in two (or even more) different chemical environments (e.g., due to different solvent shielding), producing species with different lifetimes. Normally the radiative constant of a luminescent species is independent of the chemical environment, and in such a case the pre-exponential factors are related to the fraction of species experiencing different environments. In biochemical research it is very common to consider that a multiexponential decay can result from different conformers of a single biological molecule. 

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